Pui O (Chinese: 貝澳, or 杯澳), formerly Lo Pui O (螺杯澳), is an area on Lantau Island in Hong Kong. It is a popular destination for holiday camping in Hong Kong. Visitors may also rent village houses for leisure. Located in the South Lantau, there are four main villages in Pui O, they are Lo Wai (老圍), San Wai (新圍), Lo Uk (羅屋), and Ham Tin (鹹田). Pui O is located at the edge of Lantau South Country Park.

Lo Wai, San Wai, Lo Uk and Ham Tin are recognized villages under the New Territories Small House Policy.

Pui O is a bay shaped by the Chi Ma Wan Peninsula and the lower slopes of Sunset Peak. A main river from a valley to the east and other small river gather at Pui O forming an estuary of wetland. Villagers enclosed the wetland and converted it into rice paddies. This is indicated by the name Ham Tin (鹹田; 'salty paddy field'). At the shore, a long beach (or spit) is formed by the interaction between the current of the South China Sea and the rivers.

Pui O Beach (貝澳泳灘) runs along almost the entire shoreline of Pui O. Due to the geological composition of surrounding area, the sand on the beach is mixture of black and yellow. The Hong Kong Government has constructed facilities on the upper beach for wild camping.

Lo Pui O is one of five villages of Lantau that were resettled when the coastal restriction of the Great Clearance was lifted in 1669. The other villages are Tung Sai Chung, Tai O, Shek Pik and Mui Wo.

During the Qing dynasty, villages near the shore in Hong Kong were frequently attacked by pirates. Villages in Pui O were constructed as walled villages to assist in repelling these attacks, and several of the Lantau villages, though getting a living from the sea, were by design located at some distance from it.

Tung Chung was already seen on Western maps beginning in 1815, sometimes with the romanization Poyo (see image).

29 historical buildings and features of Pui O are listed by the Antiquities and Monuments Office.