diff --git a/packages/eslint/migrations.json b/packages/eslint/migrations.json
index c9a2ee1aac98f..0be15e3c7aae7 100644
--- a/packages/eslint/migrations.json
+++ b/packages/eslint/migrations.json
@@ -24,6 +24,11 @@
       "version": "20.2.0-beta.5",
       "description": "Update TypeScript ESLint packages to v8.13.0 if they are already on v8",
       "implementation": "./src/migrations/update-20-2-0/update-typescript-eslint-v8-13-0"
+    },
+    "add-file-extensions-to-overrides": {
+      "version": "20.3.0-beta.1",
+      "description": "Update ESLint flat config to include .cjs, .mjs, .cts, and .mts files in overrides (if needed)",
+      "implementation": "./src/migrations/update-20-3-0/add-file-extensions-to-overrides"
     }
   },
   "packageJsonUpdates": {
diff --git a/packages/eslint/src/generators/utils/flat-config/ast-utils.spec.ts b/packages/eslint/src/generators/utils/flat-config/ast-utils.spec.ts
index 5f19e95f522f3..7726ffbfaf58a 100644
--- a/packages/eslint/src/generators/utils/flat-config/ast-utils.spec.ts
+++ b/packages/eslint/src/generators/utils/flat-config/ast-utils.spec.ts
@@ -125,6 +125,8 @@ describe('ast-utils', () => {
         }).map(config => ({
             ...config,
             files: [
+                "**/*.ts",
+                "**/*.tsx",
                 "**/*.cts",
                 "**/*.mts"
             ],
diff --git a/packages/eslint/src/generators/utils/flat-config/ast-utils.ts b/packages/eslint/src/generators/utils/flat-config/ast-utils.ts
index a80e493893eea..80f52c860ec4d 100644
--- a/packages/eslint/src/generators/utils/flat-config/ast-utils.ts
+++ b/packages/eslint/src/generators/utils/flat-config/ast-utils.ts
@@ -1016,6 +1016,8 @@ export function generateFlatOverride(
     rest.extends === 'plugin:@nx/javascript'
   ) {
     const newFiles = new Set(files);
+    newFiles.add('**/*.js');
+    newFiles.add('**/*.jsx');
     newFiles.add('**/*.cjs');
     newFiles.add('**/*.mjs');
     files = Array.from(newFiles);
@@ -1027,6 +1029,8 @@ export function generateFlatOverride(
     rest.extends === 'plugin:@nx/typescript'
   ) {
     const newFiles = new Set(files);
+    newFiles.add('**/*.ts');
+    newFiles.add('**/*.tsx');
     newFiles.add('**/*.cts');
     newFiles.add('**/*.mts');
     files = Array.from(newFiles);
diff --git a/packages/eslint/src/migrations/update-20-3-0/add-file-extensions-to-overrides.spec.ts b/packages/eslint/src/migrations/update-20-3-0/add-file-extensions-to-overrides.spec.ts
new file mode 100644
index 0000000000000..c9dec8aae46f0
--- /dev/null
+++ b/packages/eslint/src/migrations/update-20-3-0/add-file-extensions-to-overrides.spec.ts
@@ -0,0 +1,187 @@
+import { type Tree } from '@nx/devkit';
+import { createTreeWithEmptyWorkspace } from '@nx/devkit/testing';
+import migration from './add-file-extensions-to-overrides';
+
+describe('add-file-extensions-to-overrides', () => {
+  let tree: Tree;
+
+  beforeEach(() => {
+    tree = createTreeWithEmptyWorkspace();
+  });
+
+  it('should add .cjs, .mjs, .cts, .mts file extensions to overrides converted using convert-to-flat-config', async () => {
+    tree.write(
+      'eslint.config.js',
+      `const { FlatCompat } = require('@eslint/eslintrc');
+const js = require('@eslint/js');
+const nxEslintPlugin = require('@nx/eslint-plugin');
+
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+});
+
+module.exports = [
+  ...compat
+    .config({
+      extends: ['plugin:@nx/typescript'],
+    })
+    .map((config) => ({
+      ...config,
+      files: ['**/*.ts', '**/*.tsx'],
+      rules: {
+        ...config.rules,
+      },
+    })),
+  ...compat
+    .config({
+      extends: ['plugin:@nx/javascript'],
+    })
+    .map((config) => ({
+      ...config,
+      files: ['**/*.js', '**/*.jsx'],
+      rules: {
+        ...config.rules,
+      },
+    })),
+];`
+    );
+
+    await migration(tree);
+
+    const updated = tree.read('eslint.config.js', 'utf-8');
+    expect(updated).toMatchInlineSnapshot(`
+      "const { FlatCompat } = require('@eslint/eslintrc');
+      const js = require('@eslint/js');
+      const nxEslintPlugin = require('@nx/eslint-plugin');
+
+      const compat = new FlatCompat({
+        baseDirectory: __dirname,
+        recommendedConfig: js.configs.recommended,
+      });
+
+      module.exports = [
+        ...compat
+          .config({
+            extends: ['plugin:@nx/typescript'],
+          })
+          .map((config) => ({
+            ...config,
+            files: ['**/*.ts', '**/*.tsx', '**/*.cts', '**/*.mts'],
+            rules: {
+              ...config.rules,
+            },
+          })),
+        ...compat
+          .config({
+            extends: ['plugin:@nx/javascript'],
+          })
+          .map((config) => ({
+            ...config,
+            files: ['**/*.js', '**/*.jsx', '**/*.cjs', '**/*.mjs'],
+            rules: {
+              ...config.rules,
+            },
+          })),
+      ];"
+    `);
+  });
+
+  it('should handle duplicates', async () => {
+    tree.write(
+      'eslint.config.js',
+      `const { FlatCompat } = require('@eslint/eslintrc');
+const js = require('@eslint/js');
+const nxEslintPlugin = require('@nx/eslint-plugin');
+
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+});
+
+module.exports = [
+  ...compat
+    .config({
+      extends: ['plugin:@nx/javascript'],
+    })
+    .map((config) => ({
+      ...config,
+      files: ['**/*.js', '**/*.jsx', '**/*.mjs'],
+      rules: {
+        ...config.rules,
+      },
+    })),
+];`
+    );
+
+    await migration(tree);
+
+    const updated = tree.read('eslint.config.js', 'utf-8');
+    expect(updated).toMatchInlineSnapshot(`
+      "const { FlatCompat } = require('@eslint/eslintrc');
+      const js = require('@eslint/js');
+      const nxEslintPlugin = require('@nx/eslint-plugin');
+
+      const compat = new FlatCompat({
+        baseDirectory: __dirname,
+        recommendedConfig: js.configs.recommended,
+      });
+
+      module.exports = [
+        ...compat
+          .config({
+            extends: ['plugin:@nx/javascript'],
+          })
+          .map((config) => ({
+            ...config,
+            files: ['**/*.js', '**/*.jsx', '**/*.mjs', '**/*.cjs'],
+            rules: {
+              ...config.rules,
+            },
+          })),
+      ];"
+    `);
+  });
+
+  it('should not update if plugin:@nx/javascript and plugin:@nx/typescript are not used', async () => {
+    const original = `const { FlatCompat } = require('@eslint/eslintrc');
+const js = require('@eslint/js');
+const nxEslintPlugin = require('@nx/eslint-plugin');
+
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+  recommendedConfig: js.configs.recommended,
+});
+
+module.exports = [
+  ...compat
+    .config({
+      extends: ['plugin:@acme/foo'],
+    })
+    .map((config) => ({
+      ...config,
+      files: ['**/*.ts', '**/*.tsx'],
+      rules: {
+        ...config.rules,
+      },
+    })),
+  ...compat
+    .config({
+      extends: ['plugin:@acme/bar'],
+    })
+    .map((config) => ({
+      ...config,
+      files: ['**/*.js', '**/*.jsx'],
+      rules: {
+        ...config.rules,
+      },
+    })),
+];`;
+    tree.write('eslint.config.js', original);
+
+    await migration(tree);
+
+    const updated = tree.read('eslint.config.js', 'utf-8');
+    expect(updated).toEqual(original);
+  });
+});
diff --git a/packages/eslint/src/migrations/update-20-3-0/add-file-extensions-to-overrides.ts b/packages/eslint/src/migrations/update-20-3-0/add-file-extensions-to-overrides.ts
new file mode 100644
index 0000000000000..d2bd661cd84e0
--- /dev/null
+++ b/packages/eslint/src/migrations/update-20-3-0/add-file-extensions-to-overrides.ts
@@ -0,0 +1,97 @@
+import { type Tree } from '@nx/devkit';
+import * as ts from 'typescript';
+import { findNodes, replaceChange } from '@nx/js';
+
+export default async function (tree: Tree): Promise<void> {
+  let rootConfig: string;
+
+  // NOTE: we don't support generating ESM base config currently so they are not handled.
+  for (const candidate of ['eslint.config.js', 'eslint.config.cjs']) {
+    if (tree.exists(candidate)) {
+      rootConfig = candidate;
+      break;
+    }
+  }
+
+  if (!rootConfig) return;
+
+  updateOverrideFileExtensions(
+    tree,
+    rootConfig,
+    'plugin:@nx/typescript',
+    [`'**/*.ts'`, `'**/*.tsx'`],
+    [`'**/*.cts'`, `'**/*.mts'`]
+  );
+
+  updateOverrideFileExtensions(
+    tree,
+    rootConfig,
+    'plugin:@nx/javascript',
+    [`'**/*.js'`, `'**/*.jsx'`],
+    [`'**/*.cjs'`, `'**/*.mjs'`]
+  );
+}
+
+function updateOverrideFileExtensions(
+  tree: Tree,
+  configFile: string,
+  plugin: string,
+  matchingExts: string[],
+  newExts: string[]
+): void {
+  const content = tree.read(configFile, 'utf-8');
+  const source = ts.createSourceFile(
+    '',
+    content,
+    ts.ScriptTarget.Latest,
+    true,
+    ts.ScriptKind.JS
+  );
+  let compatNode: ts.SpreadElement;
+
+  const spreadElementNodes = findNodes(
+    source,
+    ts.SyntaxKind.SpreadElement
+  ) as ts.SpreadElement[];
+  for (const a of spreadElementNodes) {
+    const assignmentNodes = findNodes(
+      a,
+      ts.SyntaxKind.PropertyAssignment
+    ) as ts.PropertyAssignment[];
+    if (assignmentNodes.length === 0) continue;
+    for (const b of assignmentNodes) {
+      if (
+        b.name.getText() === 'extends' &&
+        b.initializer.getText().includes(plugin)
+      ) {
+        compatNode = a;
+        break;
+      }
+    }
+  }
+
+  if (compatNode) {
+    const arrayNodes = findNodes(
+      compatNode,
+      ts.SyntaxKind.ArrayLiteralExpression
+    ) as ts.ArrayLiteralExpression[];
+    for (const a of arrayNodes) {
+      if (
+        matchingExts.every((ext) => a.elements.some((e) => e.getText() === ext))
+      ) {
+        const exts = new Set(a.elements.map((e) => e.getText()));
+        for (const ext of newExts) {
+          exts.add(ext);
+        }
+        replaceChange(
+          tree,
+          source,
+          configFile,
+          a.getStart(a.getSourceFile()),
+          `[${Array.from(exts).join(', ')}]`,
+          a.getText()
+        ).getText();
+      }
+    }
+  }
+}