The Nepean River railway bridge is a heritage-listed railway bridge that carries the Main Southern railway line across Menangle Road and the Nepean River located at the outer south-western Sydney settlement of Menangle in the Wollondilly Shire local government area of New South Wales, Australia. It was designed by John Whitton as the Engineer-in-Chief, of the New South Wales Government Railways and NSW Department of Public Works. The railway bridge was built in 1863 by Messers Peto, Brassey and Betts. It is also known as Menangle rail bridge over Nepean River and Menangle Railway Bridge. The property was added to the New South Wales State Heritage Register on 2 April 1999.