Wat Phnom (Khmer: វត្តភ្នំ) ("Temple of the Mountains" or "Mountain Pagoda") is a Buddhist temple (wat) located in Phnom Penh, Cambodia. It was built in 1373, and stands 27 metres above the ground. It is the tallest religious structure in the city.

Legend relates that Daun Penh, a wealthy widow, found a large koki tree in the river. Inside the tree she found four bronze statues of the Buddha. Lady Penh constructed a small shrine on an artificial hill to protect the sacred statues. Eventually this became a sacred site and sanctuary where people would make blessings and pray.

Another account of the founding of the wat suggests King Ponhea Yat, built the sanctuary (vihear) when he moved his capital from Angkor to Phnom Penh in 1422. The prominent stupa immediately west of the sanctuary contains the ashes of the king and his royal family.

Wat Phnom is the center of celebration during Khmer New Year, and Pchum Ben

The sanctuary itself was rebuilt several times in the 19th century and again in 1926. The interior has a central altar complex with a large bronze seated Buddha surrounded by other statues, flowers, candles and items of devotion and worship. The walls are covered with murals, especially of Jataka stories of the Buddha's earlier reincarnations before his enlightenment. There are also murals depicting stories from the Reamker, the Khmer version of the Ramayana. The newer murals in the bottom tiers are somewhat balanced, traditional and modern.

The southwest corner of the vihear and stupa, is a small shrine dedicated to Lady Penh. The front is often crowded with the faithful bringing their prayers and food offerings to the woman deemed responsible for the founding of the wat.