diff --git a/packages/block/test/testdata/testnetMerge.json b/packages/block/test/testdata/testnetMerge.json
index 995d7b1d2a..e6698fa6b3 100644
--- a/packages/block/test/testdata/testnetMerge.json
+++ b/packages/block/test/testdata/testnetMerge.json
@@ -1,7 +1,6 @@
 {
   "name": "testnetMerge",
   "chainId": 55555,
-  "networkId": 55555,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "poa",
diff --git a/packages/blockchain/test/testdata/testnet.json b/packages/blockchain/test/testdata/testnet.json
index 177e9b5baa..3bf8733743 100644
--- a/packages/blockchain/test/testdata/testnet.json
+++ b/packages/blockchain/test/testdata/testnet.json
@@ -1,7 +1,6 @@
 {
   "name": "mainnet",
   "chainId": 1,
-  "networkId": 1,
   "defaultHardfork": "london",
   "consensus": {
     "type": "pow",
diff --git a/packages/client/bin/cli.ts b/packages/client/bin/cli.ts
index 6e692ca1e9..ee1eccb7be 100755
--- a/packages/client/bin/cli.ts
+++ b/packages/client/bin/cli.ts
@@ -85,8 +85,16 @@ const args: ClientOpts = yargs
     choices: networks.map((n) => n[1]).filter((el) => isNaN(parseInt(el))),
     default: 'mainnet',
   })
+  .option('chainId', {
+    describe: 'Chain ID',
+    choices: networks.map((n) => parseInt(n[0])).filter((el) => !isNaN(el)),
+    default: undefined,
+    conflicts: ['customChain', 'customGenesisState', 'gethGenesis'], // Disallows custom chain data and chainId
+  })
   .option('networkId', {
     describe: 'Network ID',
+    deprecated: true,
+    deprecate: 'use --chainId instead',
     choices: networks.map((n) => parseInt(n[0])).filter((el) => !isNaN(el)),
     default: undefined,
     conflicts: ['customChain', 'customGenesisState', 'gethGenesis'], // Disallows custom chain data and networkId
@@ -922,8 +930,9 @@ async function run() {
 
   // TODO sharding: Just initialize kzg library now, in future it can be optimized to be
   // loaded and initialized on the sharding hardfork activation
-  // Give network id precedence over network name
-  const chain = args.networkId ?? args.network ?? Chain.Mainnet
+  // Give chainId priority over networkId
+  // Give networkId precedence over network name
+  const chain = args.chainId ?? args.networkId ?? args.network ?? Chain.Mainnet
   const cryptoFunctions: CustomCrypto = {}
   const kzg = await loadKZG()
 
diff --git a/packages/client/examples/private-geth-network.md b/packages/client/examples/private-geth-network.md
index ab20204888..53eb07a96f 100644
--- a/packages/client/examples/private-geth-network.md
+++ b/packages/client/examples/private-geth-network.md
@@ -14,7 +14,7 @@ Second, get geth configured to use the genesis parameters file just updated.
 
 Now, let's run geth and ensure that its sealing blocks. Note, geth will prompt you for a password to unlock your signer account.
 
-`geth --datadir data --nat extip:[your local ip address here] --networkid 15470 --unlock [the signer account you created] --mine --nodiscover`
+`geth --datadir data --nat extip:[your local ip address here] --chainId 15470 --unlock [the signer account you created] --mine --nodiscover`
 
 You should start seeing logs like below:
 
diff --git a/packages/client/src/blockchain/chain.ts b/packages/client/src/blockchain/chain.ts
index b2adafd7b7..63f03235dd 100644
--- a/packages/client/src/blockchain/chain.ts
+++ b/packages/client/src/blockchain/chain.ts
@@ -226,10 +226,10 @@ export class Chain {
   }
 
   /**
-   * Network ID
+   * Chain ID
    */
-  get networkId(): bigint {
-    return this.config.chainCommon.networkId()
+  get chainId(): bigint {
+    return this.config.chainCommon.chainId()
   }
 
   /**
diff --git a/packages/client/src/net/protocol/ethprotocol.ts b/packages/client/src/net/protocol/ethprotocol.ts
index 2c9d0ac0d5..bc94fec3dc 100644
--- a/packages/client/src/net/protocol/ethprotocol.ts
+++ b/packages/client/src/net/protocol/ethprotocol.ts
@@ -404,7 +404,7 @@ export class EthProtocol extends Protocol {
    */
   encodeStatus(): any {
     return {
-      networkId: bigIntToUnpaddedBytes(this.chain.networkId),
+      chainId: bigIntToUnpaddedBytes(this.chain.chainId),
       td: bigIntToUnpaddedBytes(this.chain.blocks.td),
       bestHash: this.chain.blocks.latest!.hash(),
       genesisHash: this.chain.genesis.hash(),
@@ -418,7 +418,7 @@ export class EthProtocol extends Protocol {
    */
   decodeStatus(status: any): any {
     return {
-      networkId: bytesToBigInt(status.networkId),
+      chainId: bytesToBigInt(status.chainId),
       td: bytesToBigInt(status.td),
       bestHash: status.bestHash,
       genesisHash: status.genesisHash,
diff --git a/packages/client/src/net/protocol/lesprotocol.ts b/packages/client/src/net/protocol/lesprotocol.ts
index 97f4400cb9..b64324b774 100644
--- a/packages/client/src/net/protocol/lesprotocol.ts
+++ b/packages/client/src/net/protocol/lesprotocol.ts
@@ -194,7 +194,7 @@ export class LesProtocol extends Protocol {
     const forkID = [hexToBytes(forkHash), bigIntToUnpaddedBytes(nextFork ?? 0n)]
 
     return {
-      networkId: bigIntToUnpaddedBytes(this.chain.networkId),
+      chainId: bigIntToUnpaddedBytes(this.chain.chainId),
       headTd: bigIntToUnpaddedBytes(this.chain.headers.td),
       headHash: this.chain.headers.latest?.hash(),
       headNum: bigIntToUnpaddedBytes(this.chain.headers.height),
@@ -223,7 +223,7 @@ export class LesProtocol extends Protocol {
       }
     }
     return {
-      networkId: bytesToBigInt(status.networkId),
+      chainId: bytesToBigInt(status.chainId),
       headTd: bytesToBigInt(status.headTd),
       headHash: status.headHash,
       headNum: bytesToBigInt(status.headNum),
diff --git a/packages/client/src/rpc/modules/admin.ts b/packages/client/src/rpc/modules/admin.ts
index 2da9a3c846..49a5c31234 100644
--- a/packages/client/src/rpc/modules/admin.ts
+++ b/packages/client/src/rpc/modules/admin.ts
@@ -45,7 +45,7 @@ export class Admin {
     const difficulty = latestHeader.difficulty.toString()
     const genesis = bytesToHex(this._chain.genesis.hash())
     const head = bytesToHex(latestHeader.mixHash)
-    const network = this._chain.networkId.toString()
+    const network = this._chain.chainId.toString()
 
     const nodeInfo = {
       name: clientName,
diff --git a/packages/client/src/types.ts b/packages/client/src/types.ts
index bbebaabb05..0098d534f8 100644
--- a/packages/client/src/types.ts
+++ b/packages/client/src/types.ts
@@ -98,6 +98,8 @@ export type DnsNetwork = string
 
 export interface ClientOpts {
   network?: string
+  chainId?: number
+  // Deprecated, use chainId instead
   networkId?: number
   sync?: SyncMode
   lightServe?: boolean
diff --git a/packages/client/test/blockchain/chain.spec.ts b/packages/client/test/blockchain/chain.spec.ts
index 981573a9ab..2f6f945ca4 100644
--- a/packages/client/test/blockchain/chain.spec.ts
+++ b/packages/client/test/blockchain/chain.spec.ts
@@ -33,7 +33,7 @@ describe('[Chain]', () => {
   it('should retrieve chain properties', async () => {
     const chain = await Chain.create({ config })
     await chain.open()
-    assert.equal(chain.networkId, BigInt(1), 'get chain.networkId')
+    assert.equal(chain.chainId, BigInt(1), 'get chain.chainId')
     assert.equal(chain.blocks.td.toString(10), '17179869184', 'get chain.blocks.td')
     assert.equal(chain.blocks.height.toString(10), '0', 'get chain.blocks.height')
     assert.equal(
diff --git a/packages/client/test/cli/cli.spec.ts b/packages/client/test/cli/cli.spec.ts
index 2fc1987eda..cabf9ee261 100644
--- a/packages/client/test/cli/cli.spec.ts
+++ b/packages/client/test/cli/cli.spec.ts
@@ -31,7 +31,7 @@ export function clientRunHelper(
 describe('[CLI]', () => {
   // chain network tests
   it('should successfully start client with a custom network and network id', async () => {
-    const cliArgs = ['--network=sepolia', '--networkId=11155111']
+    const cliArgs = ['--network=sepolia', '--chainId=11155111']
     const onData = (message: string, child: ChildProcessWithoutNullStreams, resolve: Function) => {
       if (message.includes('Initializing Ethereumjs client')) {
         assert.ok(
@@ -648,7 +648,6 @@ describe('[CLI]', () => {
     const customChainJson = `{
       "name": "customChain",
       "chainId": 11155111,
-      "networkId": 11155111,
       "defaultHardfork": "shanghai",
       "consensus": {
         "type": "pow",
@@ -782,13 +781,13 @@ describe('[CLI]', () => {
     await clientRunHelper(cliArgs, onData, true)
   }, 5000)
   it('should not start client with conflicting parameters', async () => {
-    const cliArgs = ['--networkId', '--gethGenesis']
+    const cliArgs = ['--chainId', '--gethGenesis']
     const onData = async (
       message: string,
       child: ChildProcessWithoutNullStreams,
       resolve: Function
     ) => {
-      if (message.includes('Arguments networkId and gethGenesis are mutually exclusive')) {
+      if (message.includes('Arguments chainId and gethGenesis are mutually exclusive')) {
         assert.ok(true, 'correctly errors on conflicting arguments')
       }
       child.kill(15)
diff --git a/packages/client/test/net/protocol/ethprotocol.spec.ts b/packages/client/test/net/protocol/ethprotocol.spec.ts
index 930aa794d0..82c423e52e 100644
--- a/packages/client/test/net/protocol/ethprotocol.spec.ts
+++ b/packages/client/test/net/protocol/ethprotocol.spec.ts
@@ -32,7 +32,7 @@ describe('[EthProtocol]', () => {
     const config = new Config({ accountCache: 10000, storageCache: 1000 })
     const chain = await Chain.create({ config })
     const p = new EthProtocol({ config, chain })
-    Object.defineProperty(chain, 'networkId', {
+    Object.defineProperty(chain, 'chainId', {
       get: () => {
         return BigInt(1)
       },
@@ -53,7 +53,7 @@ describe('[EthProtocol]', () => {
     assert.deepEqual(
       p.encodeStatus(),
       {
-        networkId: hexToBytes('0x01'),
+        chainId: hexToBytes('0x01'),
         td: hexToBytes('0x64'),
         bestHash: '0xaa',
         genesisHash: '0xbb',
@@ -62,13 +62,13 @@ describe('[EthProtocol]', () => {
       'encode status'
     )
     const status = p.decodeStatus({
-      networkId: [0x01],
+      chainId: [0x01],
       td: hexToBytes('0x64'),
       bestHash: '0xaa',
       genesisHash: '0xbb',
     })
     assert.ok(
-      status.networkId === BigInt(1) &&
+      status.chainId === BigInt(1) &&
         status.td === BigInt(100) &&
         status.bestHash === '0xaa' &&
         status.genesisHash === '0xbb',
diff --git a/packages/client/test/net/protocol/lesprotocol.spec.ts b/packages/client/test/net/protocol/lesprotocol.spec.ts
index 7d9719cb5a..e147f4b5b7 100644
--- a/packages/client/test/net/protocol/lesprotocol.spec.ts
+++ b/packages/client/test/net/protocol/lesprotocol.spec.ts
@@ -33,7 +33,7 @@ describe('[LesProtocol]', () => {
       mrc: { GetBlockHeaders: { base: 10, req: 10 } },
     })
     const p = new LesProtocol({ config, chain, flow })
-    Object.defineProperty(chain, 'networkId', {
+    Object.defineProperty(chain, 'chainId', {
       get: () => {
         return BigInt(1)
       },
@@ -65,7 +65,7 @@ describe('[LesProtocol]', () => {
     })
     let status = p.encodeStatus()
     assert.ok(
-      bytesToHex(status.networkId) === '0x01' &&
+      bytesToHex(status.chainId) === '0x01' &&
         bytesToHex(status.headTd) === '0x64' &&
         status.headHash === '0xaa' &&
         bytesToHex(status.headNum) === '0x64' &&
@@ -84,10 +84,10 @@ describe('[LesProtocol]', () => {
         bytesToHex(status['flowControl/MRC'][0][2]) === '0x0a',
       'encode status'
     )
-    status = { ...status, networkId: [0x01] }
+    status = { ...status, chainId: [0x01] }
     status = p.decodeStatus(status)
     assert.ok(
-      status.networkId === BigInt(1) &&
+      status.chainId === BigInt(1) &&
         status.headTd === BigInt(100) &&
         status.headHash === '0xaa' &&
         status.headNum === BigInt(100) &&
diff --git a/packages/client/test/rpc/eth/getProof.spec.ts b/packages/client/test/rpc/eth/getProof.spec.ts
index 0c298ba2b7..9169ae06ce 100644
--- a/packages/client/test/rpc/eth/getProof.spec.ts
+++ b/packages/client/test/rpc/eth/getProof.spec.ts
@@ -42,7 +42,6 @@ const expectedProof = {
 const testnetData = {
   name: 'testnet2',
   chainId: 12345,
-  networkId: 12345,
   defaultHardfork: 'istanbul',
   consensus: {
     type: 'pow',
diff --git a/packages/client/test/sim/beaconsync.spec.ts b/packages/client/test/sim/beaconsync.spec.ts
index cbc46eb1e4..7611183123 100644
--- a/packages/client/test/sim/beaconsync.spec.ts
+++ b/packages/client/test/sim/beaconsync.spec.ts
@@ -51,7 +51,7 @@ describe('simple mainnet test run', async () => {
   }
 
   // Better add it as a option in startnetwork
-  process.env.NETWORKID = `${common.networkId()}`
+  process.env.NETWORKID = `${common.chainId()}`
   const { teardownCallBack, result } = await startNetwork(network, client, {
     filterKeywords,
     filterOutWords,
diff --git a/packages/client/test/sim/snapsync.spec.ts b/packages/client/test/sim/snapsync.spec.ts
index 81ab062c2f..e8aded7d90 100644
--- a/packages/client/test/sim/snapsync.spec.ts
+++ b/packages/client/test/sim/snapsync.spec.ts
@@ -58,7 +58,7 @@ describe('simple mainnet test run', async () => {
     process.env.EXTRA_CL_PARAMS = '--params.CAPELLA_FORK_EPOCH 0'
   }
   // Better add it as a option in startnetwork
-  process.env.NETWORKID = `${common.networkId()}`
+  process.env.NETWORKID = `${common.chainId()}`
   const { teardownCallBack, result } = await startNetwork(network, client, {
     filterKeywords,
     filterOutWords,
diff --git a/packages/client/test/testdata/common/testnet.json b/packages/client/test/testdata/common/testnet.json
index 0c7531e072..88e4a72ab5 100644
--- a/packages/client/test/testdata/common/testnet.json
+++ b/packages/client/test/testdata/common/testnet.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet",
   "chainId": 12345,
-  "networkId": 12345,
   "defaultHardfork": "byzantium",
   "consensus": {
     "type": "pow",
diff --git a/packages/common/examples/genesisData/testnet.json b/packages/common/examples/genesisData/testnet.json
index 1b208d2140..bfb6fe4974 100644
--- a/packages/common/examples/genesisData/testnet.json
+++ b/packages/common/examples/genesisData/testnet.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet1",
   "chainId": 22222,
-  "networkId": 22222,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "poa",
diff --git a/packages/common/examples/genesisData/testnet2.json b/packages/common/examples/genesisData/testnet2.json
index 2215fde86c..5eec2f59ce 100644
--- a/packages/common/examples/genesisData/testnet2.json
+++ b/packages/common/examples/genesisData/testnet2.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet2",
   "chainId": 33333,
-  "networkId": 33333,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "poa",
diff --git a/packages/common/src/chains.ts b/packages/common/src/chains.ts
index 946ed17c08..0443442b81 100644
--- a/packages/common/src/chains.ts
+++ b/packages/common/src/chains.ts
@@ -8,7 +8,6 @@ export const chains: ChainsDict = {
   mainnet: {
     name: 'mainnet',
     chainId: 1,
-    networkId: 1,
     defaultHardfork: 'shanghai',
     consensus: {
       type: 'pow',
@@ -162,7 +161,6 @@ export const chains: ChainsDict = {
   goerli: {
     name: 'goerli',
     chainId: 5,
-    networkId: 5,
     defaultHardfork: 'shanghai',
     consensus: {
       type: 'poa',
@@ -324,7 +322,6 @@ export const chains: ChainsDict = {
   sepolia: {
     name: 'sepolia',
     chainId: 11155111,
-    networkId: 11155111,
     defaultHardfork: 'shanghai',
     consensus: {
       type: 'pow',
@@ -459,7 +456,6 @@ export const chains: ChainsDict = {
   holesky: {
     name: 'holesky',
     chainId: 17000,
-    networkId: 17000,
     defaultHardfork: 'paris',
     consensus: {
       type: 'pos',
@@ -578,7 +574,6 @@ export const chains: ChainsDict = {
   kaustinen6: {
     name: 'kaustinen6',
     chainId: 69420,
-    networkId: 69420,
     defaultHardfork: 'osaka',
     consensus: {
       type: 'pos',
diff --git a/packages/common/src/common.ts b/packages/common/src/common.ts
index ddba7ecb36..33a0750450 100644
--- a/packages/common/src/common.ts
+++ b/packages/common/src/common.ts
@@ -106,7 +106,7 @@ export class Common {
           'Chain must be a string, number, or bigint when initialized with customChains passed in'
         )
       }
-      const required = ['networkId', 'genesis', 'hardforks', 'bootstrapNodes']
+      const required = ['chainId', 'genesis', 'hardforks', 'bootstrapNodes']
       for (const param of required) {
         if (!(param in chain)) {
           throw new Error(`Missing required chain parameter: ${param}`)
@@ -847,14 +847,6 @@ export class Common {
     return this._chainParams.name
   }
 
-  /**
-   * Returns the Id of current network
-   * @returns network Id
-   */
-  networkId(): bigint {
-    return BigInt(this._chainParams.networkId)
-  }
-
   /**
    * Returns the additionally activated EIPs
    * (by using the `eips` constructor option)
diff --git a/packages/common/src/constructors.ts b/packages/common/src/constructors.ts
index 4fbb87208d..5ee817a7b5 100644
--- a/packages/common/src/constructors.ts
+++ b/packages/common/src/constructors.ts
@@ -48,7 +48,6 @@ export function createCustomCommon(
         {
           name: CustomChain.PolygonMainnet,
           chainId: 137,
-          networkId: 137,
         },
         opts
       )
@@ -58,7 +57,6 @@ export function createCustomCommon(
         {
           name: CustomChain.PolygonMumbai,
           chainId: 80001,
-          networkId: 80001,
         },
         opts
       )
@@ -68,7 +66,6 @@ export function createCustomCommon(
         {
           name: CustomChain.ArbitrumOne,
           chainId: 42161,
-          networkId: 42161,
         },
         opts
       )
@@ -78,7 +75,6 @@ export function createCustomCommon(
         {
           name: CustomChain.xDaiChain,
           chainId: 100,
-          networkId: 100,
         },
         opts
       )
@@ -89,7 +85,6 @@ export function createCustomCommon(
         {
           name: CustomChain.OptimisticKovan,
           chainId: 69,
-          networkId: 69,
         },
         opts
       )
@@ -100,7 +95,6 @@ export function createCustomCommon(
         {
           name: CustomChain.OptimisticEthereum,
           chainId: 10,
-          networkId: 10,
         },
         // Optimism has not implemented the London hardfork yet (targeting Q1.22)
         { hardfork: Hardfork.Berlin, ...opts }
diff --git a/packages/common/src/types.ts b/packages/common/src/types.ts
index a17d6b3d98..88c28f96d2 100644
--- a/packages/common/src/types.ts
+++ b/packages/common/src/types.ts
@@ -28,7 +28,6 @@ type ConsensusConfig = {
 export interface ChainConfig {
   name: string
   chainId: number | bigint
-  networkId: number | bigint
   defaultHardfork?: string
   comment?: string
   url?: string
diff --git a/packages/common/src/utils.ts b/packages/common/src/utils.ts
index 91b6db3931..975a256c02 100644
--- a/packages/common/src/utils.ts
+++ b/packages/common/src/utils.ts
@@ -88,7 +88,6 @@ function parseGethParams(json: any, mergeForkIdPostMerge: boolean = true) {
   const params = {
     name,
     chainId,
-    networkId: chainId,
     depositContractAddress,
     genesis: {
       timestamp,
diff --git a/packages/common/test/chains.spec.ts b/packages/common/test/chains.spec.ts
index 3a2da8caea..e0d25554b7 100644
--- a/packages/common/test/chains.spec.ts
+++ b/packages/common/test/chains.spec.ts
@@ -14,7 +14,6 @@ describe('[Common/Chains]: Initialization / Chain params', () => {
     let c = new Common({ chain: 'mainnet' })
     assert.equal(c.chainName(), 'mainnet', 'should initialize with chain name')
     assert.equal(c.chainId(), BigInt(1), 'should return correct chain Id')
-    assert.equal(c.networkId(), BigInt(1), 'should return correct network Id')
     assert.equal(c.hardfork(), Hardfork.Shanghai, 'should set hardfork to current default hardfork')
     assert.equal(
       c.hardfork(),
@@ -30,7 +29,6 @@ describe('[Common/Chains]: Initialization / Chain params', () => {
     const c = new Common({ chain: Chain.Mainnet })
     assert.equal(c.chainName(), 'mainnet', 'should initialize with chain name')
     assert.equal(c.chainId(), BigInt(1), 'should return correct chain Id')
-    assert.equal(c.networkId(), BigInt(1), 'should return correct network Id')
     assert.equal(c.hardfork(), Hardfork.Shanghai, 'should set hardfork to current default hardfork')
     assert.equal(
       c.hardfork(),
diff --git a/packages/common/test/customChains.spec.ts b/packages/common/test/customChains.spec.ts
index 5efa8a83aa..71bdd0d9ae 100644
--- a/packages/common/test/customChains.spec.ts
+++ b/packages/common/test/customChains.spec.ts
@@ -21,7 +21,6 @@ describe('[Common]: Custom chains', () => {
     const c = new Common({ chain: testnet, hardfork: Hardfork.Byzantium })
     assert.equal(c.chainName(), 'testnet', 'should initialize with chain name')
     assert.equal(c.chainId(), BigInt(12345), 'should return correct chain Id')
-    assert.equal(c.networkId(), BigInt(12345), 'should return correct network Id')
     assert.equal(c.hardforks()[3]['block'], 3, 'should return correct hardfork data')
     assert.equal(c.bootstrapNodes()[1].ip, '10.0.0.2', 'should return a bootstrap node array')
   })
@@ -42,7 +41,7 @@ describe('[Common]: Custom chains', () => {
   it('custom() -> base functionality', () => {
     const mainnetCommon = new Common({ chain: Chain.Mainnet })
 
-    const customChainParams = { name: 'custom', chainId: 123, networkId: 678 }
+    const customChainParams = { name: 'custom', chainId: 123 }
     const customChainCommon = createCustomCommon(customChainParams, {
       hardfork: Hardfork.Byzantium,
     })
@@ -50,7 +49,6 @@ describe('[Common]: Custom chains', () => {
     // From custom chain params
     assert.equal(customChainCommon.chainName(), customChainParams.name)
     assert.equal(customChainCommon.chainId(), BigInt(customChainParams.chainId))
-    assert.equal(customChainCommon.networkId(), BigInt(customChainParams.networkId))
 
     // Fallback params from mainnet
     assert.equal(customChainCommon.genesis(), mainnetCommon.genesis())
@@ -63,12 +61,12 @@ describe('[Common]: Custom chains', () => {
 
   it('custom() -> behavior', () => {
     let common = createCustomCommon({ chainId: 123 })
-    assert.deepEqual(common.networkId(), BigInt(1), 'should default to mainnet base chain')
+    assert.equal(common.consensusAlgorithm(), 'casper', 'should default to mainnet base chain')
     assert.equal(common.chainName(), 'custom-chain', 'should set default custom chain name')
 
     common = createCustomCommon(CustomChain.PolygonMumbai)
     assert.deepEqual(
-      common.networkId(),
+      common.chainId(),
       BigInt(80001),
       'supported chain -> should initialize with correct chain ID'
     )
@@ -158,7 +156,6 @@ describe('[Common]: Custom chains', () => {
     const customChainParams: Partial<ChainConfig> = {
       name: 'custom',
       chainId: 123,
-      networkId: 678,
       depositContractAddress: '0x4242424242424242424242424242424242424242',
     }
     const customChainCommon = createCustomCommon(customChainParams, {
diff --git a/packages/common/test/customCrypto.spec.ts b/packages/common/test/customCrypto.spec.ts
index 0783026c84..7e5ae55f40 100644
--- a/packages/common/test/customCrypto.spec.ts
+++ b/packages/common/test/customCrypto.spec.ts
@@ -41,7 +41,7 @@ describe('[Common]: Custom Crypto', () => {
     msg = 'Should still work on a copied instance'
     assert.deepEqual(c.copy().customCrypto.keccak256!(value), new Uint8Array([2, 1]), msg)
 
-    const customChainParams = { name: 'custom', chainId: 123, networkId: 678 }
+    const customChainParams = { name: 'custom', chainId: 123 }
     c = createCustomCommon(customChainParams, { customCrypto })
     msg = 'Should initialize with custom keccak256 function and use properly (custom() constructor)'
     assert.deepEqual(c.customCrypto.keccak256!(value), new Uint8Array([2, 1]), msg)
diff --git a/packages/common/test/data/merge/testnetMerge.json b/packages/common/test/data/merge/testnetMerge.json
index 995d7b1d2a..e6698fa6b3 100644
--- a/packages/common/test/data/merge/testnetMerge.json
+++ b/packages/common/test/data/merge/testnetMerge.json
@@ -1,7 +1,6 @@
 {
   "name": "testnetMerge",
   "chainId": 55555,
-  "networkId": 55555,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "poa",
diff --git a/packages/common/test/data/merge/testnetPOS.json b/packages/common/test/data/merge/testnetPOS.json
index 549193be0b..325c973033 100644
--- a/packages/common/test/data/merge/testnetPOS.json
+++ b/packages/common/test/data/merge/testnetPOS.json
@@ -1,7 +1,6 @@
 {
   "name": "testnetPOS",
   "chainId": 66666,
-  "networkId": 66666,
   "defaultHardfork": "chainstart",
   "consensus": {
     "type": "pos",
diff --git a/packages/common/test/data/testnet.json b/packages/common/test/data/testnet.json
index 0c7531e072..88e4a72ab5 100644
--- a/packages/common/test/data/testnet.json
+++ b/packages/common/test/data/testnet.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet",
   "chainId": 12345,
-  "networkId": 12345,
   "defaultHardfork": "byzantium",
   "consensus": {
     "type": "pow",
diff --git a/packages/common/test/data/testnet2.json b/packages/common/test/data/testnet2.json
index ddbb57107a..a76bc09f7c 100644
--- a/packages/common/test/data/testnet2.json
+++ b/packages/common/test/data/testnet2.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet2",
   "chainId": 22222,
-  "networkId": 22222,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "poa",
diff --git a/packages/common/test/data/testnet3.json b/packages/common/test/data/testnet3.json
index c8b59ac9f2..7a10962950 100644
--- a/packages/common/test/data/testnet3.json
+++ b/packages/common/test/data/testnet3.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet3",
   "chainId": 33333,
-  "networkId": 33333,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "poa",
diff --git a/packages/devp2p/src/protocol/eth.ts b/packages/devp2p/src/protocol/eth.ts
index 4e4a6deeb1..c2dd7e0c92 100644
--- a/packages/devp2p/src/protocol/eth.ts
+++ b/packages/devp2p/src/protocol/eth.ts
@@ -203,13 +203,13 @@ export class ETH extends Protocol {
     )
 
     const status: {
-      networkId: Uint8Array | Uint8Array[]
+      chainId: Uint8Array | Uint8Array[]
       td: Uint8Array
       bestHash: Uint8Array
       genesisHash: Uint8Array
       forkId?: Uint8Array | Uint8Array[]
     } = {
-      networkId: this._peerStatus[1],
+      chainId: this._peerStatus[1],
       td: this._peerStatus[2] as Uint8Array,
       bestHash: this._peerStatus[3] as Uint8Array,
       genesisHash: this._peerStatus[4] as Uint8Array,
diff --git a/packages/devp2p/src/protocol/les.ts b/packages/devp2p/src/protocol/les.ts
index 357c8d5c6d..a0950a7f17 100644
--- a/packages/devp2p/src/protocol/les.ts
+++ b/packages/devp2p/src/protocol/les.ts
@@ -127,8 +127,8 @@ export class LES extends Protocol {
       'STATUS'
     )
     assertEq(
-      this._status['networkId'],
-      this._peerStatus['networkId'],
+      this._status['chainId'],
+      this._peerStatus['chainId'],
       'NetworkId mismatch',
       this.debug.bind(this),
       'STATUS'
@@ -153,7 +153,7 @@ export class LES extends Protocol {
 
   _getStatusString(status: LES.Status) {
     let sStr = `[V:${bytesToInt(status['protocolVersion'])}, `
-    sStr += `NID:${bytesToInt(status['networkId'] as Uint8Array)}, HTD:${bytesToInt(
+    sStr += `NID:${bytesToInt(status['chainId'] as Uint8Array)}, HTD:${bytesToInt(
       status['headTd']
     )}, `
     sStr += `HeadH:${bytesToHex(status['headHash'])}, HeadN:${bytesToInt(status['headNum'])}, `
@@ -184,7 +184,7 @@ export class LES extends Protocol {
       status['announceType'] = intToBytes(DEFAULT_ANNOUNCE_TYPE)
     }
     status['protocolVersion'] = intToBytes(this._version)
-    status['networkId'] = bigIntToBytes(this._peer.common.chainId())
+    status['chainId'] = bigIntToBytes(this._peer.common.chainId())
 
     this._status = status
 
@@ -284,7 +284,7 @@ export namespace LES {
   export interface Status {
     [key: string]: any
     protocolVersion: Uint8Array
-    networkId: Uint8Array
+    chainId: Uint8Array
     headTd: Uint8Array
     headHash: Uint8Array
     headNum: Uint8Array
diff --git a/packages/tx/examples/custom-chain-tx.ts b/packages/tx/examples/custom-chain-tx.ts
index b4f4c64a7c..8378dccf3a 100644
--- a/packages/tx/examples/custom-chain-tx.ts
+++ b/packages/tx/examples/custom-chain-tx.ts
@@ -6,12 +6,10 @@ import { hexToBytes } from '@ethereumjs/util'
 // In this example we create a transaction for a custom network.
 
 // This custom network has the same params as mainnet,
-// except for name, chainId, and networkId,
-// so we use the `Common.custom` method.
+// except for name, chainId, so we use the `Common.custom` method.
 const customCommon = createCustomCommon(
   {
     name: 'my-network',
-    networkId: 123,
     chainId: 2134,
   },
   {
diff --git a/packages/tx/src/baseTransaction.ts b/packages/tx/src/baseTransaction.ts
index 9f8c70f80d..2597dfa885 100644
--- a/packages/tx/src/baseTransaction.ts
+++ b/packages/tx/src/baseTransaction.ts
@@ -398,7 +398,6 @@ export abstract class BaseTransaction<T extends TransactionType>
           return createCustomCommon(
             {
               name: 'custom-chain',
-              networkId: chainIdBigInt,
               chainId: chainIdBigInt,
             },
             { baseChain: this.DEFAULT_CHAIN }
diff --git a/packages/vm/test/api/EIPs/eip-6800-verkle.spec.ts b/packages/vm/test/api/EIPs/eip-6800-verkle.spec.ts
index 8e4213ada6..86792cce4a 100644
--- a/packages/vm/test/api/EIPs/eip-6800-verkle.spec.ts
+++ b/packages/vm/test/api/EIPs/eip-6800-verkle.spec.ts
@@ -13,7 +13,7 @@ import { VM } from '../../../src'
 import type { BlockData } from '@ethereumjs/block'
 import type { PrefixedHexString } from '@ethereumjs/util'
 
-const customChainParams = { name: 'custom', chainId: 69420, networkId: 678 }
+const customChainParams = { name: 'custom', chainId: 69420 }
 const common = createCustomCommon(customChainParams, {
   hardfork: Hardfork.Cancun,
   eips: [2935, 4895, 6800],
diff --git a/packages/vm/test/api/index.spec.ts b/packages/vm/test/api/index.spec.ts
index f35e792fe5..7d824395cf 100644
--- a/packages/vm/test/api/index.spec.ts
+++ b/packages/vm/test/api/index.spec.ts
@@ -182,7 +182,7 @@ describe('VM -> common (chain, HFs, EIPs)', () => {
   })
 
   it('should accept a custom chain config (createCustomCommon() static constructor)', async () => {
-    const customChainParams = { name: 'custom', chainId: 123, networkId: 678 }
+    const customChainParams = { name: 'custom', chainId: 123 }
     const common = createCustomCommon(customChainParams, {
       baseChain: 'mainnet',
       hardfork: 'byzantium',
diff --git a/packages/vm/test/api/runBlock.spec.ts b/packages/vm/test/api/runBlock.spec.ts
index 78702db2ce..27b76b0a0a 100644
--- a/packages/vm/test/api/runBlock.spec.ts
+++ b/packages/vm/test/api/runBlock.spec.ts
@@ -139,7 +139,7 @@ describe('runBlock() -> successful API parameter usage', async () => {
   })
 
   it('PoW block, Common custom chain (createCustomCommon() static constructor)', async () => {
-    const customChainParams = { name: 'custom', chainId: 123, networkId: 678 }
+    const customChainParams = { name: 'custom', chainId: 123 }
     const common = createCustomCommon(customChainParams, {
       baseChain: 'mainnet',
       hardfork: 'berlin',
diff --git a/packages/vm/test/api/testdata/testnet.json b/packages/vm/test/api/testdata/testnet.json
index b270831712..c503a09d32 100644
--- a/packages/vm/test/api/testdata/testnet.json
+++ b/packages/vm/test/api/testdata/testnet.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet",
   "chainId": 12345,
-  "networkId": 12345,
   "defaultHardfork": "byzantium",
   "consensus": {
     "type": "pow",
diff --git a/packages/vm/test/api/testdata/testnet2.json b/packages/vm/test/api/testdata/testnet2.json
index bbef65a16d..6d8db16448 100644
--- a/packages/vm/test/api/testdata/testnet2.json
+++ b/packages/vm/test/api/testdata/testnet2.json
@@ -1,7 +1,6 @@
 {
   "name": "testnet2",
   "chainId": 22222,
-  "networkId": 22222,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "pos",
diff --git a/packages/vm/test/api/testdata/testnetMerge.json b/packages/vm/test/api/testdata/testnetMerge.json
index 995d7b1d2a..e6698fa6b3 100644
--- a/packages/vm/test/api/testdata/testnetMerge.json
+++ b/packages/vm/test/api/testdata/testnetMerge.json
@@ -1,7 +1,6 @@
 {
   "name": "testnetMerge",
   "chainId": 55555,
-  "networkId": 55555,
   "defaultHardfork": "istanbul",
   "consensus": {
     "type": "poa",