Po Toi O () is a small fishing village and a bay at Clear Water Bay Peninsula, Sai Kung, New Territories, Hong Kong.
The village is situated at a bay shaped like a sack, thus earning its name Po Toi (meaning a "sack").
Po Toi O is a recognized village under the New Territories Small House Policy.
Po Toi O was historically a multi-clan village with surnames Cheung (), Chan (), Chong () and others.
This small fishing village has two seafood restaurants and is popular with tourists.
There is a Hung Shing Temple in Po Toi O. The temple was probably built in 1663. A Kung So () building adjacent to the temple was built in 1740 and was used to deal with village affairs and served as a school until the 1930s. The temple is a Grade III historic building.
Po Toi O can be reached by land using Po Toi O Chuen Road (). The village is served by green minibus 16 - Po Lam, Tseung Kwan O to Po Toi O.