diff --git a/changelog.md b/changelog.md
index 21c296a8..0ddfba26 100644
--- a/changelog.md
+++ b/changelog.md
@@ -5,6 +5,7 @@ Features
 ---------
 * Add `--ssh-options` CLI argument to pass extra options with `--ssh-jump`.
 * Make `ssh_jump` a DSN query parameter.
+* Warn on unknown DSN query parameters.
 
 
 Bug Fixes
diff --git a/mycli/cli_runner.py b/mycli/cli_runner.py
index f03b71c9..84565124 100644
--- a/mycli/cli_runner.py
+++ b/mycli/cli_runner.py
@@ -21,6 +21,21 @@
 
 ClientFactory = Callable[..., Any]
 ENV_VAR_PATTERN = re.compile(r'^\$\{([A-Za-z_][A-Za-z0-9_]*)\}$')
+KNOWN_DSN_QUERY_PARAMS = {
+    'character_set',
+    'keepalive_ticks',
+    'socket',
+    'ssh_jump',
+    'ssl',
+    'ssl_ca',
+    'ssl_capath',
+    'ssl_cert',
+    'ssl_cipher',
+    'ssl_key',
+    'ssl_mode',
+    'ssl_verify_server_cert',
+    'tls_version',
+}
 
 
 class DsnAliasEnvVarError(ValueError):
@@ -79,7 +94,10 @@ def expand_dsn_alias_env_vars(
     except ValueError as exc:
         raise DsnAliasEnvVarError(f'Port in DSN alias {alias_name} must be an integer.') from exc
 
-    params = {key: [expand_dsn_alias_env_var(value, alias_name) or '' for value in values] for key, values in parse_qs(uri.query).items()}
+    params = {
+        key: [expand_dsn_alias_env_var(value, alias_name) or '' for value in values]
+        for key, values in parse_qs(uri.query, keep_blank_values=True).items()
+    }
 
     return (
         expand_dsn_alias_env_var(unquote(username) if username is not None else None, alias_name),
@@ -200,7 +218,7 @@ def run_from_cli_args(cli_args: 'CliArgs', client_factory: ClientFactory) -> Non
             dsn_host = uri.hostname
             dsn_port = uri.port
             dsn_database = uri.path[1:]
-            dsn_params = parse_qs(uri.query) if uri.query else {}
+            dsn_params = parse_qs(uri.query, keep_blank_values=True) if uri.query else {}
 
         if not database:
             database = dsn_database
@@ -214,6 +232,13 @@ def run_from_cli_args(cli_args: 'CliArgs', client_factory: ClientFactory) -> Non
         if not cli_args.port:
             cli_args.port = dsn_port
 
+        if unknown_dsn_params := sorted(set(dsn_params) - KNOWN_DSN_QUERY_PARAMS):
+            click.secho(
+                f'Warning: Ignored unknown DSN URI query parameters: {", ".join(unknown_dsn_params)}.',
+                err=True,
+                fg='yellow',
+            )
+
         if params := dsn_params.get('ssl'):
             click.secho(
                 'Warning: The "ssl" DSN URI parameter is deprecated and will be removed in a future release. '
diff --git a/test/pytests/test_cli_runner.py b/test/pytests/test_cli_runner.py
index efba80a2..f1879070 100644
--- a/test/pytests/test_cli_runner.py
+++ b/test/pytests/test_cli_runner.py
@@ -269,6 +269,70 @@ def test_run_from_cli_args_does_not_expand_unbraced_dsn_alias_env_vars(
     assert client.connect_calls[-1]['user'] == '$MYCLI_TEST_DSN_USER'
 
 
+def test_run_from_cli_args_warns_about_unknown_dsn_query_parameter(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    cli_args = make_cli_args()
+    cli_args.dsn = 'mysql://user@host/db?unknown=value'
+    client = DummyMyCli()
+    secho_calls: list[tuple[str, dict[str, Any]]] = []
+    monkeypatch.setattr(cli_runner.click, 'secho', lambda text, **kwargs: secho_calls.append((text, kwargs)))
+
+    run_with_client(monkeypatch, cli_args, client)
+
+    assert client.connect_calls[-1]['database'] == 'db'
+    assert secho_calls == [
+        (
+            'Warning: Ignored unknown DSN URI query parameters: unknown.',
+            {'err': True, 'fg': 'yellow'},
+        )
+    ]
+
+
+def test_run_from_cli_args_warns_once_about_sorted_unknown_dsn_query_parameters(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    cli_args = make_cli_args()
+    cli_args.dsn = 'mysql://user@host/db?zzz=1&aaa&character_set=utf8&aaa=2'
+    client = DummyMyCli()
+    secho_calls: list[tuple[str, dict[str, Any]]] = []
+    monkeypatch.setattr(cli_runner.click, 'secho', lambda text, **kwargs: secho_calls.append((text, kwargs)))
+
+    run_with_client(monkeypatch, cli_args, client)
+
+    assert client.connect_calls[-1]['character_set'] == 'utf8'
+    assert secho_calls == [
+        (
+            'Warning: Ignored unknown DSN URI query parameters: aaa, zzz.',
+            {'err': True, 'fg': 'yellow'},
+        )
+    ]
+
+
+def test_run_from_cli_args_warns_about_unknown_alias_dsn_query_parameter_with_env_expansion(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    cli_args = make_cli_args()
+    cli_args.dsn = 'prod'
+    monkeypatch.setenv('MYCLI_TEST_DSN_CHARSET', 'utf8')
+    config = default_config()
+    config['main'] = {**config['main'], 'expand_dsn_alias_env_vars': 'true'}
+    config['alias_dsn'] = {'prod': 'mysql://user@host/db?unknown=value&character_set=${MYCLI_TEST_DSN_CHARSET}'}
+    client = DummyMyCli(config=config)
+    secho_calls: list[tuple[str, dict[str, Any]]] = []
+    monkeypatch.setattr(cli_runner.click, 'secho', lambda text, **kwargs: secho_calls.append((text, kwargs)))
+
+    run_with_client(monkeypatch, cli_args, client)
+
+    assert client.connect_calls[-1]['character_set'] == 'utf8'
+    assert secho_calls == [
+        (
+            'Warning: Ignored unknown DSN URI query parameters: unknown.',
+            {'err': True, 'fg': 'yellow'},
+        )
+    ]
+
+
 def test_run_from_cli_args_reports_missing_dsn_alias_env_var(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
@@ -380,6 +444,21 @@ def test_run_from_cli_args_maps_dsn_ssh_jump_parameter(monkeypatch: pytest.Monke
     assert client.connect_calls[-1]['ssh_jump'] == 'bastion'
 
 
+def test_run_from_cli_args_does_not_warn_about_known_dsn_query_parameter(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    cli_args = make_cli_args()
+    cli_args.dsn = 'mysql://user@host/db?ssh_jump=bastion'
+    client = DummyMyCli()
+    secho_calls: list[tuple[str, dict[str, Any]]] = []
+    monkeypatch.setattr(cli_runner.click, 'secho', lambda text, **kwargs: secho_calls.append((text, kwargs)))
+
+    run_with_client(monkeypatch, cli_args, client)
+
+    assert client.connect_calls[-1]['ssh_jump'] == 'bastion'
+    assert secho_calls == []
+
+
 def test_run_from_cli_args_prefers_cli_ssh_jump_over_dsn_parameter(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None: