diff --git a/playwright/_impl/_browser_type.py b/playwright/_impl/_browser_type.py
index 93173160c..eb92cdb18 100644
--- a/playwright/_impl/_browser_type.py
+++ b/playwright/_impl/_browser_type.py
@@ -356,6 +356,8 @@ def normalize_launch_params(params: Dict) -> None:
         if params["ignoreDefaultArgs"] is True:
             params["ignoreAllDefaultArgs"] = True
             del params["ignoreDefaultArgs"]
+        elif params["ignoreDefaultArgs"] is False:
+            del params["ignoreDefaultArgs"]
     if "executablePath" in params:
         params["executablePath"] = str(Path(params["executablePath"]))
     if "downloadsPath" in params:
diff --git a/tests/test_ignore_default_args_bool.py b/tests/test_ignore_default_args_bool.py
new file mode 100644
index 000000000..54f8fd21c
--- /dev/null
+++ b/tests/test_ignore_default_args_bool.py
@@ -0,0 +1,29 @@
+def test_ignore_default_args_false_is_removed():
+    # Unit test: no driver/browser needed.
+    from playwright._impl._browser_type import normalize_launch_params
+
+    params = {"ignoreDefaultArgs": False}
+    normalize_launch_params(params)
+
+    assert "ignoreDefaultArgs" not in params
+    assert "ignoreAllDefaultArgs" not in params
+
+
+def test_ignore_default_args_true_sets_ignore_all_default_args():
+    from playwright._impl._browser_type import normalize_launch_params
+
+    params = {"ignoreDefaultArgs": True}
+    normalize_launch_params(params)
+
+    assert "ignoreDefaultArgs" not in params
+    assert params["ignoreAllDefaultArgs"] is True
+
+
+def test_ignore_default_args_list_is_preserved():
+    from playwright._impl._browser_type import normalize_launch_params
+
+    params = {"ignoreDefaultArgs": ["--mute-audio"]}
+    normalize_launch_params(params)
+
+    assert params["ignoreDefaultArgs"] == ["--mute-audio"]
+    assert "ignoreAllDefaultArgs" not in params