diff --git a/narwhals/_dask/expr.py b/narwhals/_dask/expr.py
index c111b5153..941f0e7a4 100644
--- a/narwhals/_dask/expr.py
+++ b/narwhals/_dask/expr.py
@@ -485,6 +485,13 @@ def clip(
             returns_scalar=False,
         )
 
+    def diff(self: Self) -> Self:
+        return self._from_call(
+            lambda _input: _input.diff(),
+            "diff",
+            returns_scalar=False,
+        )
+
     def n_unique(self: Self) -> Self:
         return self._from_call(
             lambda _input: _input.nunique(dropna=False),
diff --git a/tests/expr_and_series/diff_test.py b/tests/expr_and_series/diff_test.py
index 41f59c34d..f38b96e00 100644
--- a/tests/expr_and_series/diff_test.py
+++ b/tests/expr_and_series/diff_test.py
@@ -15,8 +15,6 @@
 
 
 def test_diff(constructor: Any, request: Any) -> None:
-    if "dask" in str(constructor):
-        request.applymarker(pytest.mark.xfail)
     if "pyarrow_table_constructor" in str(constructor) and parse_version(
         pa.__version__
     ) < (13,):