diff --git a/.changeset/five-colts-rescue.md b/.changeset/five-colts-rescue.md
new file mode 100644
index 000000000000..61761796751c
--- /dev/null
+++ b/.changeset/five-colts-rescue.md
@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Fixes a routing issue with partially truncated dynamic segments.
diff --git a/packages/astro/src/core/routing/manifest/create.ts b/packages/astro/src/core/routing/manifest/create.ts
index 00b87a049d39..e30440fa4f8d 100644
--- a/packages/astro/src/core/routing/manifest/create.ts
+++ b/packages/astro/src/core/routing/manifest/create.ts
@@ -401,9 +401,7 @@ function createFileBasedRoutes(
 				const pathname = segments.every((segment) => segment.length === 1 && !segment[0].dynamic)
 					? `/${segments.map((segment) => segment[0].content).join('/')}`
 					: null;
-				const route = `/${segments
-					.map(([{ dynamic, content }]) => (dynamic ? `[${content}]` : content))
-					.join('/')}`.toLowerCase();
+				const route = joinSegments(segments);
 				routes.push({
 					route,
 					isIndex: item.isIndex,
@@ -478,9 +476,7 @@ function createInjectedRoutes({ settings, cwd }: CreateRouteManifestParams): Pri
 			.flat()
 			.filter((p) => p.dynamic)
 			.map((p) => p.content);
-		const route = `/${segments
-			.map(([{ dynamic, content }]) => (dynamic ? `[${content}]` : content))
-			.join('/')}`.toLowerCase();
+		const route = joinSegments(segments);
 
 		routes[priority].push({
 			type,
@@ -536,9 +532,7 @@ function createRedirectRoutes(
 			.flat()
 			.filter((p) => p.dynamic)
 			.map((p) => p.content);
-		const route = `/${segments
-			.map(([{ dynamic, content }]) => (dynamic ? `[${content}]` : content))
-			.join('/')}`.toLowerCase();
+		const route = joinSegments(segments);
 
 		let destination: string;
 		if (typeof to === 'string') {
@@ -899,3 +893,11 @@ function computeRoutePriority(config: AstroConfig): RoutePriorityOverride {
 	}
 	return 'legacy';
 }
+
+function joinSegments(segments: RoutePart[][]): string {
+	const arr = segments.map((segment) => {
+		return segment.map((rp) => (rp.dynamic ? `[${rp.content}]` : rp.content)).join('');
+	});
+
+	return `/${arr.join('/')}`.toLowerCase();
+}
diff --git a/packages/astro/test/units/routing/manifest.test.js b/packages/astro/test/units/routing/manifest.test.js
index 91816d1bc670..e5fa35729938 100644
--- a/packages/astro/test/units/routing/manifest.test.js
+++ b/packages/astro/test/units/routing/manifest.test.js
@@ -144,8 +144,8 @@ describe('routing - createRouteManifest', () => {
 
 		assertRouteRelations(getManifestRoutes(manifest), [
 			['/', '/[...rest]'],
-			['/static', '/static-'],
-			['/static-', '/[dynamic]'],
+			['/static', '/static-[dynamic]'],
+			['/static-[dynamic]', '/[dynamic]'],
 			['/static', '/[dynamic]'],
 			['/static', '/[...rest]'],
 			['/[dynamic]', '/[...rest]'],
@@ -567,4 +567,48 @@ describe('routing - createRouteManifest', () => {
 			},
 		]);
 	});
+
+	it('should concatenate each part of the segment. issues#10122', async () => {
+		const fs = createFs(
+			{
+				'/src/pages/a-[b].astro': `<h1>test</h1>`,
+				'/src/pages/blog/a-[b].233.ts': ``,
+			},
+			root
+		);
+
+		const settings = await createBasicSettings({
+			root: fileURLToPath(root),
+			output: 'server',
+			base: '/search',
+			trailingSlash: 'never',
+			redirects: {
+				'/posts/a-[b].233': '/blog/a-[b].233',
+			},
+			experimental: {
+				globalRoutePriority: true,
+			},
+		});
+
+		settings.injectedRoutes = [
+			{
+				pattern: '/[c]-d',
+				entrypoint: '@lib/legacy/dynamic.astro',
+				priority: 'normal',
+			},
+		];
+
+		const manifest = createRouteManifest({
+			cwd: fileURLToPath(root),
+			settings,
+			fsMod: fs,
+		});
+
+		assert.deepEqual(getManifestRoutes(manifest), [
+			{ type: 'endpoint', route: '/blog/a-[b].233' },
+			{ type: 'redirect', route: '/posts/a-[b].233' },
+			{ type: 'page', route: '/[c]-d' },
+			{ type: 'page', route: '/a-[b]' },
+		]);
+	});
 });