diff --git a/app/manifest/v2/_base.json b/app/manifest/v2/_base.json
index bc8cfc6e3533..c0b25efeeb94 100644
--- a/app/manifest/v2/_base.json
+++ b/app/manifest/v2/_base.json
@@ -35,7 +35,8 @@
         "lockdown-install.js",
         "lockdown-run.js",
         "lockdown-more.js",
-        "contentscript.js"
+        "contentscript.js",
+        "inpage.js"
       ],
       "run_at": "document_start",
       "all_frames": true
diff --git a/app/scripts/contentscript.js b/app/scripts/contentscript.js
index dda5e7a74efe..8d63ec70ac5e 100644
--- a/app/scripts/contentscript.js
+++ b/app/scripts/contentscript.js
@@ -9,16 +9,6 @@ import { checkForLastError } from '../../shared/modules/browser-runtime.utils';
 import { isManifestV3 } from '../../shared/modules/mv3.utils';
 import shouldInjectProvider from '../../shared/modules/provider-injection';
 
-// These require calls need to use require to be statically recognized by browserify
-const fs = require('fs');
-const path = require('path');
-
-const inpageContent = fs.readFileSync(
-  path.join(__dirname, '..', '..', 'dist', 'chrome', 'inpage.js'),
-  'utf8',
-);
-const inpageBundle = inpageContent;
-
 // contexts
 const CONTENT_SCRIPT = 'metamask-contentscript';
 const INPAGE = 'metamask-inpage';
@@ -61,24 +51,6 @@ let extensionMux,
   pageMux,
   pageChannel;
 
-/**
- * Injects a script tag into the current document
- *
- * @param {string} content - Code to be executed in the current document
- */
-function injectScript(content) {
-  try {
-    const container = document.head || document.documentElement;
-    const scriptTag = document.createElement('script');
-    scriptTag.setAttribute('async', 'false');
-    scriptTag.textContent = content;
-    container.insertBefore(scriptTag, container.children[0]);
-    container.removeChild(scriptTag);
-  } catch (error) {
-    console.error('MetaMask: Provider injection failed.', error);
-  }
-}
-
 /**
  * PHISHING STREAM LOGIC
  */
@@ -545,9 +517,6 @@ const start = () => {
   }
 
   if (shouldInjectProvider()) {
-    if (!isManifestV3) {
-      injectScript(inpageBundle);
-    }
     initStreams();
 
     // https://bugs.chromium.org/p/chromium/issues/detail?id=1457040
diff --git a/development/build/scripts.js b/development/build/scripts.js
index eeb61bdb8f87..cd641658cc88 100644
--- a/development/build/scripts.js
+++ b/development/build/scripts.js
@@ -2,7 +2,7 @@
 
 const { callbackify } = require('util');
 const path = require('path');
-const { writeFileSync, readFileSync } = require('fs');
+const { writeFileSync, readFileSync, unlinkSync } = require('fs');
 const EventEmitter = require('events');
 const assert = require('assert');
 const gulp = require('gulp');
@@ -43,6 +43,7 @@ const {
   getBuildName,
   getBuildAppId,
   getBuildIcon,
+  makeSelfInjecting,
 } = require('./utils');
 
 const {
@@ -471,6 +472,26 @@ function createScriptTasks({
         version,
         applyLavaMoat,
       }),
+      () => {
+        // MV3 injects inpage into the tab's main world, but in MV2 we need
+        // to do it manually:
+        if (process.env.ENABLE_MV3) {
+          return;
+        }
+        // stringify inpage.js into itself, and then make it inject itself into the page
+        browserPlatforms.forEach((browser) => {
+          makeSelfInjecting(
+            path.join(__dirname, `../../dist/${browser}/${inpage}.js`),
+          );
+        });
+        // delete the inpage.js source map, as it no longer represents inpage.js
+        // and so `yarn source-map-explorer` can't handle it. It's also not
+        // useful anyway, as inpage.js is injected as a `script.textContent`,
+        // and not tracked in Sentry or browsers devtools anyway.
+        unlinkSync(
+          path.join(__dirname, `../../dist/sourcemaps/${inpage}.js.map`),
+        );
+      },
       createNormalBundle({
         buildTarget,
         buildType,
diff --git a/development/build/utils.js b/development/build/utils.js
index eeba5ae67cc9..07349c88db28 100644
--- a/development/build/utils.js
+++ b/development/build/utils.js
@@ -1,5 +1,5 @@
 const path = require('path');
-const { readFileSync } = require('fs');
+const { readFileSync, writeFileSync } = require('fs');
 const semver = require('semver');
 const { capitalize } = require('lodash');
 const { loadBuildTypesConfig } = require('../lib/build-type');
@@ -287,6 +287,21 @@ function getBuildIcon({ buildType }) {
   const svg = readFileSync(svgLogoPath, 'utf8');
   return `data:image/svg+xml,${encodeURIComponent(svg)}`;
 }
+/**
+ * Takes the given JavaScript file at `filePath` and replaces its contents with
+ * a script that injects the original file contents into the document in which
+ * the file is loaded. Useful for MV2 extensions to run scripts synchronously in the
+ * "MAIN" world.
+ *
+ * @param {string} filePath - The path to the file to convert to a self-injecting
+ * script.
+ */
+function makeSelfInjecting(filePath) {
+  const fileContents = readFileSync(filePath, 'utf8');
+  const textContent = JSON.stringify(fileContents);
+  const js = `{let d=document,s=d.createElement('script');s.textContent=${textContent};d.documentElement.appendChild(s).remove();}`;
+  writeFileSync(filePath, js, 'utf8');
+}
 
 module.exports = {
   getBrowserVersionMap,
@@ -299,4 +314,5 @@ module.exports = {
   logError,
   getPathInsideNodeModules,
   wrapAgainstScuttling,
+  makeSelfInjecting,
 };
diff --git a/development/sourcemap-validator.js b/development/sourcemap-validator.js
index 87c74a1236f8..585144100942 100755
--- a/development/sourcemap-validator.js
+++ b/development/sourcemap-validator.js
@@ -25,8 +25,8 @@ async function start() {
     `common-0.js`,
     `background-0.js`,
     `ui-0.js`,
-    // `contentscript.js`, skipped because the validator is erroneously sampling the inlined `inpage.js` script
-    `inpage.js`,
+    `contentscript.js`,
+    // `inpage.js`, skipped because the validator can't sample the inlined `inpage.js` script
   ];
   let valid = true;