diff --git a/.changes/next-release/enhancement-login-27668.json b/.changes/next-release/enhancement-login-27668.json
new file mode 100644
index 000000000000..d34fab79d458
--- /dev/null
+++ b/.changes/next-release/enhancement-login-27668.json
@@ -0,0 +1,5 @@
+{
+  "type": "enhancement",
+  "category": "``login``",
+  "description": "Prevent ``aws login`` from updating a profile with a different style of existing credentials."
+}
diff --git a/awscli/customizations/login/login.py b/awscli/customizations/login/login.py
index 4959b6d9c104..f102ab2ae795 100644
--- a/awscli/customizations/login/login.py
+++ b/awscli/customizations/login/login.py
@@ -20,6 +20,7 @@
     RequiredInputValidator,
 )
 from awscli.customizations.configure.writer import ConfigFileWriter
+from awscli.customizations.exceptions import ConfigurationError
 from awscli.customizations.login.utils import (
     CrossDeviceLoginTokenFetcher,
     LoginType,
@@ -96,6 +97,10 @@ def _run_main(self, parsed_args, parsed_globals):
         if profile_name not in self._session.available_profiles:
             self._session._profile_map[profile_name] = {}
 
+        # Abort if the profile is already configured with a different style
+        # of credentials, since they'd still have precedence over login
+        self.ensure_profile_does_not_have_existing_credentials(profile_name)
+
         config = botocore.config.Config(
             region_name=region,
             signature_version=botocore.UNSIGNED,
@@ -177,6 +182,37 @@ def accept_change_to_existing_profile_if_needed(
             else:
                 uni_print('Invalid response. Please enter "y" or "n"')
 
+    def ensure_profile_does_not_have_existing_credentials(self, profile_name):
+        """
+        Raises an error if the specified profile is already
+        configured with a different style of credentials.
+        """
+        config = self._session.full_config['profiles'].get(profile_name, {})
+        existing_credentials_style = None
+
+        if 'web_identity_token_file' in config:
+            existing_credentials_style = 'Web Identity'
+        elif 'sso_role_name' in config or 'sso_account_id' in config:
+            existing_credentials_style = 'SSO'
+        elif 'aws_access_key_id' in config:
+            existing_credentials_style = 'Access Key'
+        elif 'role_arn' in config:
+            existing_credentials_style = 'Assume Role'
+        elif 'credential_process' in config:
+            existing_credentials_style = 'Credential Process'
+
+        if existing_credentials_style:
+            raise ConfigurationError(
+                f'Profile \'{profile_name}\' is already configured '
+                f'with {existing_credentials_style} credentials.\n\n'
+                f'You may run \'aws login --profile new-profile-name\' to '
+                f'create a new profile with the specified name. Otherwise you '
+                f'must first manually remove the existing credentials '
+                f'from \'{profile_name}\'.\n'
+            )
+
+        return False
+
     @staticmethod
     def resolve_sign_in_type(parsed_args):
         if parsed_args.remote:
diff --git a/tests/functional/login/test_login.py b/tests/functional/login/test_login.py
index 29c870b72e51..a89fa0a31670 100644
--- a/tests/functional/login/test_login.py
+++ b/tests/functional/login/test_login.py
@@ -6,6 +6,7 @@
 
 import pytest
 
+from awscli.customizations.exceptions import ConfigurationError
 from awscli.customizations.login.login import LoginCommand
 
 DEFAULT_ARGS = Namespace(remote=False)
@@ -230,3 +231,68 @@ def test_new_profile_without_region(
         },
         'configfile',
     )
+
+
+@pytest.mark.parametrize(
+    'profile_config,expected_to_abort',
+    [
+        pytest.param({}, False, id="Empty profile"),
+        pytest.param(
+            {'login_session': 'arn:aws:iam::0123456789012:user/Admin'},
+            False,
+            id="Existing login profile",
+        ),
+        pytest.param(
+            {'web_identity_token_file': '/path'},
+            True,
+            id="Web Identity Token profile",
+        ),
+        pytest.param({'sso_role_name': 'role'}, True, id="SSO profile"),
+        pytest.param(
+            {'aws_access_key_id': 'AKIAIOSFODNN7EXAMPLE'},
+            True,
+            id="IAM access key profile",
+        ),
+        pytest.param(
+            {'role_arn': 'arn:aws:iam::123456789012:role/MyRole'},
+            True,
+            id="Assume role profile",
+        ),
+        pytest.param(
+            {'credential_process': '/path/to/credential/process'},
+            True,
+            id="Credential process profile",
+        ),
+    ],
+)
+@mock.patch('awscli.customizations.login.utils.get_base_sign_in_uri')
+@mock.patch(
+    'awscli.customizations.login.utils.SameDeviceLoginTokenFetcher.fetch_token'
+)
+def test_abort_if_profile_has_existing_credentials(
+    mock_token_fetcher,
+    mock_base_sign_in_uri,
+    mock_login_command,
+    mock_session,
+    mock_token_loader,
+    profile_config,
+    expected_to_abort,
+):
+    mock_base_sign_in_uri.return_value = 'https://foo'
+    mock_token_fetcher.return_value = (
+        {
+            'accessToken': 'access_token',
+            'idToken': SAMPLE_ID_TOKEN,
+            'expiresIn': 3600,
+        },
+        'arn:aws:iam::0123456789012:user/Admin',
+    )
+    mock_session.full_config = {'profiles': {'profile-name': profile_config}}
+
+    if expected_to_abort:
+        with pytest.raises(ConfigurationError):
+            mock_login_command._run_main(DEFAULT_ARGS, DEFAULT_GLOBAL_ARGS)
+            mock_token_fetcher.assert_not_called()
+    else:
+        mock_login_command._run_main(DEFAULT_ARGS, DEFAULT_GLOBAL_ARGS)
+        mock_token_fetcher.assert_called_once()