diff --git a/pydantic_settings/sources/providers/cli.py b/pydantic_settings/sources/providers/cli.py
index 7f05ce43..39c0e91e 100644
--- a/pydantic_settings/sources/providers/cli.py
+++ b/pydantic_settings/sources/providers/cli.py
@@ -546,7 +546,7 @@ def _resolve_parsed_args(self, parsed_args: dict[str, list[str] | str]) -> list[
                 parsed_args[field_name] = self._merge_parsed_list(val, field_name)
             elif field_name.endswith(':subcommand') and val is not None:
                 selected_subcommands.append(self._parser_map[field_name][val].dest)
-            elif self.cli_kebab_case == 'all':
+            elif self.cli_kebab_case == 'all' and isinstance(val, str):
                 snake_val = val.replace('-', '_')
                 cli_arg = self._parser_map.get(field_name, {}).get(None)
                 if (
diff --git a/tests/test_source_cli.py b/tests/test_source_cli.py
index 65c9a672..42518ec8 100644
--- a/tests/test_source_cli.py
+++ b/tests/test_source_cli.py
@@ -2703,6 +2703,22 @@ class SettingsAll(BaseSettings):
         CliApp.run(SettingsAll, cli_args=['--example', 'example_a', '--mybool=true'])
 
 
+def test_cli_kebab_case_all_with_implicit_flag():
+    class Settings(BaseSettings):
+        model_config = SettingsConfigDict(cli_kebab_case='all')
+        test_bool_flag: CliImplicitFlag[bool]
+
+    assert CliApp.run(
+        Settings,
+        cli_args=['--test-bool-flag'],
+    ).model_dump() == {'test_bool_flag': True}
+
+    assert CliApp.run(
+        Settings,
+        cli_args=['--no-test-bool-flag'],
+    ).model_dump() == {'test_bool_flag': False}
+
+
 def test_cli_with_unbalanced_brackets_in_json_string():
     class StrToStrDictOptions(BaseSettings):
         nested: dict[str, str]