diff --git a/diffly/cli.py b/diffly/cli.py
index 07299c8..d3560eb 100644
--- a/diffly/cli.py
+++ b/diffly/cli.py
@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
 import datetime as dt
+import warnings
 from pathlib import Path
 from typing import Annotated
 
@@ -121,7 +122,7 @@ def main(
             ),
         ),
     ] = False,
-    hidden_columns: Annotated[
+    hidden_column: Annotated[
         list[str],
         typer.Option(
             help=(
@@ -130,6 +131,10 @@ def main(
             )
         ),
     ] = [],
+    hidden_columns: Annotated[
+        list[str],
+        typer.Option(hidden=True),
+    ] = [],
     metric: Annotated[
         list[str],
         typer.Option(
@@ -141,6 +146,13 @@ def main(
     ] = [],
 ) -> None:
     """Compare two `parquet` files and print the comparison result."""
+    if hidden_columns:
+        warnings.warn(
+            "`--hidden-columns` is deprecated, use `--hidden-column` instead.",
+            FutureWarning,
+        )
+        hidden_column = [*hidden_column, *hidden_columns]
+
     for name in metric:
         if name not in DEFAULT_METRICS:
             raise typer.BadParameter(
@@ -164,7 +176,7 @@ def main(
         left_name=left_name,
         right_name=right_name,
         slim=slim,
-        hidden_columns=hidden_columns,
+        hidden_columns=hidden_column,
         metrics=metrics,
     )
     if output_json:
diff --git a/tests/cli/test_cli.py b/tests/cli/test_cli.py
index 84de072..c65320c 100644
--- a/tests/cli/test_cli.py
+++ b/tests/cli/test_cli.py
@@ -58,6 +58,28 @@ def test_cli_smoke(tmp_path: Path, output_json: bool) -> None:
         assert result.output == comparison.summary().format(pretty=True) + "\n"
 
 
+def test_cli_hidden_columns_alias_warns(tmp_path: Path) -> None:
+    df = pl.DataFrame({"id": [1, 2], "secret": ["a", "b"]})
+    df.write_parquet(tmp_path / "left.parquet")
+    df.write_parquet(tmp_path / "right.parquet")
+
+    with pytest.warns(FutureWarning, match="--hidden-columns.*deprecated"):
+        result = runner.invoke(
+            app,
+            [
+                str(tmp_path / "left.parquet"),
+                str(tmp_path / "right.parquet"),
+                "--primary-key",
+                "id",
+                "--hidden-columns",
+                "secret",
+            ],
+            catch_exceptions=False,
+        )
+
+    assert result.exit_code == 0
+
+
 def test_cli_unknown_metric(tmp_path: Path) -> None:
     left = pl.DataFrame({"id": [1, 2], "x": [1.0, 2.0]})
     right = pl.DataFrame({"id": [1, 2], "x": [1.0, 3.0]})