diff --git a/astrbot/dashboard/services/auth_service.py b/astrbot/dashboard/services/auth_service.py
index bc6cbde50..856662acb 100644
--- a/astrbot/dashboard/services/auth_service.py
+++ b/astrbot/dashboard/services/auth_service.py
@@ -369,6 +369,12 @@ class AuthService:
         if not new_pwd and not new_username:
             return self.error("新用户名和新密码不能同时为空")
 
+        username_to_save = None
+        if new_username is not None and new_username != "":
+            if not isinstance(new_username, str) or len(new_username.strip()) < 3:
+                return self.error("用户名长度至少3位")
+            username_to_save = new_username.strip()
+
         if new_pwd:
             if not isinstance(new_pwd, str):
                 return self.error("新密码无效")
@@ -384,8 +390,8 @@ class AuthService:
             await set_password_change_required(self.db, self.config, False)
             if is_totp_enabled(self.config):
                 await revoke_user_trusted_devices(self.db)
-        if new_username:
-            self.config["dashboard"]["username"] = new_username
+        if username_to_save:
+            self.config["dashboard"]["username"] = username_to_save
 
         self.config.save_config()
 
diff --git a/tests/test_dashboard.py b/tests/test_dashboard.py
index 16356fbab..87d4ce006 100644
--- a/tests/test_dashboard.py
+++ b/tests/test_dashboard.py
@@ -1360,6 +1360,105 @@ async def test_generated_password_requires_password_change_until_changed(
         )
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    ("endpoint", "method"),
+    [
+        ("/api/auth/account/edit", "post"),
+        ("/api/v1/auth/account", "patch"),
+    ],
+)
+@pytest.mark.parametrize("new_username", ["ab", "   "])
+async def test_account_edit_rejects_invalid_username(
+    app: FastAPIAppAdapter,
+    core_lifecycle_td: AstrBotCoreLifecycle,
+    endpoint: str,
+    method: str,
+    new_username: str,
+):
+    original_dashboard_config = copy.deepcopy(
+        core_lifecycle_td.astrbot_config["dashboard"]
+    )
+    test_client = app.test_client()
+    current_username = core_lifecycle_td.astrbot_config["dashboard"]["username"]
+    current_password = _resolve_dashboard_password(core_lifecycle_td)
+
+    try:
+        login_response = await test_client.post(
+            "/api/auth/login",
+            json={"username": current_username, "password": current_password},
+        )
+        login_data = await login_response.get_json()
+        assert login_data["status"] == "ok"
+        headers = {"Authorization": f"Bearer {login_data['data']['token']}"}
+
+        payload = {
+            "password": current_password,
+            "new_password": "",
+            "confirm_password": "",
+            "new_username": new_username,
+        }
+        request = getattr(test_client, method)
+        response = await request(endpoint, headers=headers, json=payload)
+        data = await response.get_json()
+
+        assert data["status"] == "error"
+        assert data["message"] == "用户名长度至少3位"
+        assert (
+            core_lifecycle_td.astrbot_config["dashboard"]["username"]
+            == (original_dashboard_config["username"])
+        )
+    finally:
+        await _restore_dashboard_password_state(
+            core_lifecycle_td,
+            original_dashboard_config,
+        )
+
+
+@pytest.mark.asyncio
+async def test_account_edit_trims_valid_username(
+    app: FastAPIAppAdapter,
+    core_lifecycle_td: AstrBotCoreLifecycle,
+):
+    original_dashboard_config = copy.deepcopy(
+        core_lifecycle_td.astrbot_config["dashboard"]
+    )
+    test_client = app.test_client()
+    current_username = core_lifecycle_td.astrbot_config["dashboard"]["username"]
+    current_password = _resolve_dashboard_password(core_lifecycle_td)
+
+    try:
+        login_response = await test_client.post(
+            "/api/auth/login",
+            json={"username": current_username, "password": current_password},
+        )
+        login_data = await login_response.get_json()
+        assert login_data["status"] == "ok"
+        headers = {"Authorization": f"Bearer {login_data['data']['token']}"}
+
+        response = await test_client.post(
+            "/api/auth/account/edit",
+            headers=headers,
+            json={
+                "password": current_password,
+                "new_password": "",
+                "confirm_password": "",
+                "new_username": "  astrbot-admin  ",
+            },
+        )
+        data = await response.get_json()
+
+        assert data["status"] == "ok"
+        assert core_lifecycle_td.astrbot_config["dashboard"]["username"] == (
+            "astrbot-admin"
+        )
+    finally:
+        await _restore_dashboard_password_state(
+            core_lifecycle_td,
+            original_dashboard_config,
+        )
+
+
 @pytest.mark.asyncio
 async def test_local_setup_can_skip_default_password_auth(
     app: FastAPIAppAdapter,