Randolph Brook is a tributary of the Millstone River in northern Franklin Park, New Jersey, United States.
Randolph Brook starts at 40°32′6″N 74°33′38″W / 40.53500°N 74.56056°W / 40.53500; -74.56056,[1] near Randolph Road. It crosses Randolph Road and Westons Canal Road before flowing under the Delaware and Raritan Canal and draining into the Millstone River at 40°33′3″N 74°32′53″W / 40.55083°N 74.54806°W / 40.55083; -74.54806.[1]