diff --git a/datafusion/functions-nested/src/concat.rs b/datafusion/functions-nested/src/concat.rs
index c3dc4c67cf12c..8d06140889a55 100644
--- a/datafusion/functions-nested/src/concat.rs
+++ b/datafusion/functions-nested/src/concat.rs
@@ -317,10 +317,23 @@ impl ScalarUDFImpl for ArrayConcat {
     }
 
     fn coerce_types(&self, arg_types: &[DataType]) -> Result<Vec<DataType>> {
-        let base_type = base_type(&self.return_type(arg_types)?);
+        let return_type = self.return_type(arg_types)?;
+        let base_type = base_type(&return_type);
         let coercion = Some(&ListCoercion::FixedSizedListToList);
+        // When the return type is a `LargeList`, the outer container of every
+        // input must be widened to `LargeList` as well. Otherwise
+        // `array_concat_inner` would later try to downcast a `List` argument
+        // to `GenericListArray<i64>` and fail.
+        let promote_to_large_list = matches!(return_type, DataType::LargeList(_));
         let arg_types = arg_types.iter().map(|arg_type| {
-            coerced_type_with_base_type_only(arg_type, &base_type, coercion)
+            let coerced =
+                coerced_type_with_base_type_only(arg_type, &base_type, coercion);
+            match coerced {
+                DataType::List(field) if promote_to_large_list => {
+                    DataType::LargeList(field)
+                }
+                other => other,
+            }
         });
 
         Ok(arg_types.collect())
diff --git a/datafusion/sqllogictest/test_files/array/array_concat.slt b/datafusion/sqllogictest/test_files/array/array_concat.slt
index 0f847811615c7..168b307a1e636 100644
--- a/datafusion/sqllogictest/test_files/array/array_concat.slt
+++ b/datafusion/sqllogictest/test_files/array/array_concat.slt
@@ -121,6 +121,38 @@ select
 ----
 [1, 2, 3] List(Utf8View)
 
+# Concatenating mixed list and large list — return type widens to LargeList
+query ?T
+select
+    array_concat(make_array(1, 2), arrow_cast([3, 4], 'LargeList(Int64)')),
+    arrow_typeof(array_concat(make_array(1, 2), arrow_cast([3, 4], 'LargeList(Int64)')));
+----
+[1, 2, 3, 4] LargeList(Int64)
+
+# Reverse argument order: LargeList first, plain list second
+query ?T
+select
+    array_concat(arrow_cast([1, 2], 'LargeList(Int64)'), make_array(3, 4)),
+    arrow_typeof(array_concat(arrow_cast([1, 2], 'LargeList(Int64)'), make_array(3, 4)));
+----
+[1, 2, 3, 4] LargeList(Int64)
+
+# FixedSizeList combined with LargeList — also widens to LargeList
+query ?T
+select
+    array_concat(arrow_cast([1, 2], 'FixedSizeList(2, Int64)'), arrow_cast([3, 4], 'LargeList(Int64)')),
+    arrow_typeof(array_concat(arrow_cast([1, 2], 'FixedSizeList(2, Int64)'), arrow_cast([3, 4], 'LargeList(Int64)')));
+----
+[1, 2, 3, 4] LargeList(Int64)
+
+# Three-way mix: List, LargeList, List
+query ?T
+select
+    array_concat(make_array(1, 2), arrow_cast([3], 'LargeList(Int64)'), make_array(4, 5)),
+    arrow_typeof(array_concat(make_array(1, 2), arrow_cast([3], 'LargeList(Int64)'), make_array(4, 5)));
+----
+[1, 2, 3, 4, 5] LargeList(Int64)
+
 # array_concat with NULL elements inside arrays
 query ?
 select array_concat([1, NULL, 3], [NULL, 5]);