diff --git a/doc/source/whatsnew/v1.0.1.rst b/doc/source/whatsnew/v1.0.1.rst
index 9e78ff03f5f67..31bc1cefcb292 100644
--- a/doc/source/whatsnew/v1.0.1.rst
+++ b/doc/source/whatsnew/v1.0.1.rst
@@ -126,7 +126,7 @@ ExtensionArray
 
 Other
 ^^^^^
--
+- Regression fixed in objTOJSON.c fix return-type warning (:issue:`31463`)
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/_libs/src/ujson/python/objToJSON.c b/pandas/_libs/src/ujson/python/objToJSON.c
index c5ac279ed3243..5c5b80648aed1 100644
--- a/pandas/_libs/src/ujson/python/objToJSON.c
+++ b/pandas/_libs/src/ujson/python/objToJSON.c
@@ -178,6 +178,8 @@ void *initObjToJSON(void) {
 
     /* Initialise numpy API */
     import_array();
+    // GH 31463
+    return NULL;
 }
 
 static TypeContext *createTypeContext(void) {