diff --git a/app/Http/Controllers/Api/Client/AccountController.php b/app/Http/Controllers/Api/Client/AccountController.php
index 644b80541..627c493ee 100644
--- a/app/Http/Controllers/Api/Client/AccountController.php
+++ b/app/Http/Controllers/Api/Client/AccountController.php
@@ -5,6 +5,7 @@ namespace App\Http\Controllers\Api\Client;
 use App\Facades\Activity;
 use App\Http\Requests\Api\Client\Account\UpdateEmailRequest;
 use App\Http\Requests\Api\Client\Account\UpdatePasswordRequest;
+use App\Http\Requests\Api\Client\Account\UpdateUsernameRequest;
 use App\Services\Users\UserUpdateService;
 use App\Transformers\Api\Client\UserTransformer;
 use Illuminate\Auth\AuthManager;
@@ -36,6 +37,25 @@ class AccountController extends ClientApiController
             ->toArray();
     }
 
+    /**
+     * Update username
+     *
+     * Update the authenticated user's username.
+     */
+    public function updateUsername(UpdateUsernameRequest $request): JsonResponse
+    {
+        $original = $request->user()->username;
+        $this->updateService->handle($request->user(), $request->validated());
+
+        if ($original !== $request->input('username')) {
+            Activity::event('user:account.username-changed')
+                ->property(['old' => $original, 'new' => $request->input('username')])
+                ->log();
+        }
+
+        return new JsonResponse([], Response::HTTP_NO_CONTENT);
+    }
+
     /**
      * Update email
      *
diff --git a/app/Http/Requests/Api/Client/Account/UpdateUsernameRequest.php b/app/Http/Requests/Api/Client/Account/UpdateUsernameRequest.php
new file mode 100644
index 000000000..430fa3c71
--- /dev/null
+++ b/app/Http/Requests/Api/Client/Account/UpdateUsernameRequest.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Http\Requests\Api\Client\Account;
+
+use App\Exceptions\Http\Base\InvalidPasswordProvidedException;
+use App\Http\Requests\Api\Client\ClientApiRequest;
+use App\Models\User;
+use Illuminate\Container\Container;
+use Illuminate\Contracts\Hashing\Hasher;
+
+class UpdateUsernameRequest extends ClientApiRequest
+{
+    /**
+     * @throws InvalidPasswordProvidedException
+     */
+    public function authorize(): bool
+    {
+        if (!parent::authorize()) {
+            return false;
+        }
+
+        $hasher = Container::getInstance()->make(Hasher::class);
+
+        // Verify password matches when changing password or email.
+        if (!$hasher->check($this->input('password'), $this->user()->password)) {
+            throw new InvalidPasswordProvidedException(trans('validation.internal.invalid_password'));
+        }
+
+        return true;
+    }
+
+    public function rules(): array
+    {
+        $rules = User::getRulesForUpdate($this->user());
+
+        return ['username' => $rules['username']];
+    }
+}
diff --git a/lang/en/activity.php b/lang/en/activity.php
index 4b3cdb339..464854f00 100644
--- a/lang/en/activity.php
+++ b/lang/en/activity.php
@@ -21,6 +21,7 @@ return [
     ],
     'user' => [
         'account' => [
+            'username-changed' => 'Changed username from <b>:old</b> to <b>:new</b>',
             'email-changed' => 'Changed email from <b>:old</b> to <b>:new</b>',
             'password-changed' => 'Changed password',
         ],
diff --git a/routes/api-client.php b/routes/api-client.php
index c3510ec66..9b15a29e6 100644
--- a/routes/api-client.php
+++ b/routes/api-client.php
@@ -21,6 +21,7 @@ Route::get('/permissions', [Client\ClientController::class, 'permissions']);
 Route::prefix('/account')->middleware(AccountSubject::class)->group(function () {
     Route::get('/', [Client\AccountController::class, 'index'])->name('api:client.account');
 
+    Route::put('/username', [Client\AccountController::class, 'updateUsername'])->name('api:client.account.update-username');
     Route::put('/email', [Client\AccountController::class, 'updateEmail'])->name('api:client.account.update-email');
     Route::put('/password', [Client\AccountController::class, 'updatePassword'])->name('api:client.account.update-password');