diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py
index 988c1d25259bc..8ef5f516cd737 100644
--- a/python/pyspark/sql/functions.py
+++ b/python/pyspark/sql/functions.py
@@ -2108,7 +2108,8 @@ def udf(f=None, returnType=StringType()):
         can fail on special rows, the workaround is to incorporate the condition into the functions.
 
     :param f: python function if used as a standalone function
-    :param returnType: a :class:`pyspark.sql.types.DataType` object
+    :param returnType: the return type of the registered user-defined function. The value can be
+        either a :class:`pyspark.sql.types.DataType` object or a DDL-formatted type string.
 
     >>> from pyspark.sql.types import IntegerType
     >>> slen = udf(lambda s: len(s), IntegerType())
@@ -2148,7 +2149,8 @@ def pandas_udf(f=None, returnType=None, functionType=None):
     Creates a vectorized user defined function (UDF).
 
     :param f: user-defined function. A python function if used as a standalone function
-    :param returnType: a :class:`pyspark.sql.types.DataType` object
+    :param returnType: the return type of the registered user-defined function. The value can be
+        either a :class:`pyspark.sql.types.DataType` object or a DDL-formatted type string.
     :param functionType: an enum value in :class:`pyspark.sql.functions.PandasUDFType`.
                          Default: SCALAR.
 
diff --git a/python/pyspark/sql/udf.py b/python/pyspark/sql/udf.py
index 1cb91334b38ea..c77f19f89a442 100644
--- a/python/pyspark/sql/udf.py
+++ b/python/pyspark/sql/udf.py
@@ -206,7 +206,8 @@ def register(self, name, f, returnType=None):
         :param f: a Python function, or a user-defined function. The user-defined function can
             be either row-at-a-time or vectorized. See :meth:`pyspark.sql.functions.udf` and
             :meth:`pyspark.sql.functions.pandas_udf`.
-        :param returnType: the return type of the registered user-defined function.
+        :param returnType: the return type of the registered user-defined function. The value can
+            be either a :class:`pyspark.sql.types.DataType` object or a DDL-formatted type string.
         :return: a user-defined function.
 
         `returnType` can be optionally specified when `f` is a Python function but not
@@ -303,7 +304,8 @@ def registerJavaFunction(self, name, javaClassName, returnType=None):
 
         :param name: name of the user-defined function
         :param javaClassName: fully qualified name of java class
-        :param returnType: a :class:`pyspark.sql.types.DataType` object
+        :param returnType: the return type of the registered Java function. The value can be either
+            a :class:`pyspark.sql.types.DataType` object or a DDL-formatted type string.
 
         >>> from pyspark.sql.types import IntegerType
         >>> spark.udf.registerJavaFunction(