diff --git a/packages/angular/cli/src/commands/add/cli.ts b/packages/angular/cli/src/commands/add/cli.ts
index 136704947e69..dd186c46b397 100644
--- a/packages/angular/cli/src/commands/add/cli.ts
+++ b/packages/angular/cli/src/commands/add/cli.ts
@@ -16,6 +16,7 @@ import npa from 'npm-package-arg';
 import semver, { Range, compare, intersects, prerelease, satisfies, valid } from 'semver';
 import { Argv } from 'yargs';
 import {
+  CommandModuleError,
   CommandModuleImplementation,
   Options,
   OtherOptions,
@@ -131,6 +132,17 @@ export default class AddCommandModule
         type: 'boolean',
         default: false,
       })
+      .check(({ registry }) => {
+        if (registry === undefined) {
+          return true;
+        }
+
+        if (typeof registry === 'string' && URL.canParse(registry)) {
+          return true;
+        }
+
+        throw new CommandModuleError('Option --registry must be a valid URL.');
+      })
       // Prior to downloading we don't know the full schema and therefore we cannot be strict on the options.
       // Possibly in the future update the logic to use the following syntax:
       // `ng add @angular/localize -- --package-options`.
diff --git a/tests/e2e/tests/commands/add/registry-option.ts b/tests/e2e/tests/commands/add/registry-option.ts
index dc336cdd5b30..1343cebf4dd1 100644
--- a/tests/e2e/tests/commands/add/registry-option.ts
+++ b/tests/e2e/tests/commands/add/registry-option.ts
@@ -1,11 +1,37 @@
 import { getGlobalVariable } from '../../../utils/env';
 import { expectFileToExist } from '../../../utils/fs';
-import { ng } from '../../../utils/process';
+import { execAndCaptureError, ng } from '../../../utils/process';
 import { expectToFail } from '../../../utils/utils';
 
 export default async function () {
   const testRegistry = getGlobalVariable('package-registry');
 
+  // Validate that a non-URL registry string fails with a validation error
+  const error = await execAndCaptureError('ng', [
+    'add',
+    '--registry=not-a-valid-url',
+    '@angular/pwa',
+    '--skip-confirmation',
+  ]);
+  if (!error.message.includes('Option --registry must be a valid URL.')) {
+    throw new Error(
+      `Expected registry validation error, but got different error: ${error.message}`,
+    );
+  }
+
+  // Validate that an empty registry string fails with a validation error
+  const errorEmpty = await execAndCaptureError('ng', [
+    'add',
+    '--registry=',
+    '@angular/pwa',
+    '--skip-confirmation',
+  ]);
+  if (!errorEmpty.message.includes('Option --registry must be a valid URL.')) {
+    throw new Error(
+      `Expected registry validation error for empty string, but got: ${errorEmpty.message}`,
+    );
+  }
+
   // Set an invalid registry
   process.env['NPM_CONFIG_REGISTRY'] = 'http://127.0.0.1:9999';