The Tuen Mun River () is a river in Tuen Mun, New Territories, Hong Kong. It has many tributaries, with major ones coming from Lam Tei, Kau Keng Shan, Hung Shui Hang and Nai Wai. It flows south, bisecting Tuen Mun New Town. It eventually feeds into the Tuen Mun Typhoon Shelter, which is part of Castle Peak Bay.