diff --git a/crates/polars-ops/src/series/ops/horizontal.rs b/crates/polars-ops/src/series/ops/horizontal.rs
index 739330ad0aed..deb71f44e736 100644
--- a/crates/polars-ops/src/series/ops/horizontal.rs
+++ b/crates/polars-ops/src/series/ops/horizontal.rs
@@ -350,7 +350,10 @@ pub fn mean_horizontal(
         // All remaining must be numeric (or null).
         for col in &columns[first_non_null_idx + 1..] {
             let dtype = col.dtype();
-            if !(dtype.is_numeric()
+            if !ignore_nulls && dtype == &DataType::Null {
+                // The presence of a single null column guarantees the output is all-null.
+                return null_with_supertype(columns, true);
+            } else if !(dtype.is_numeric()
                 || dtype.is_decimal()
                 || dtype.is_bool()
                 || dtype.is_temporal()