Khao Yoi (Thai: เขาย้อย, pronounced [kʰǎw jɔ́ːj]) is a district (amphoe) in the northern part of Phetchaburi province, western Thailand.

[1] The name of the district comes from the limestone hill called Khao Yoi which is just off Phetkasem highway.

The district is divided into 10 sub-districts (tambons), which are further subdivided into 59 villages (mubans).

The sub-district municipality (thesaban tambon) Khao Yoi covers parts of tambons Khao Yoi, Sa Phang, Bang Khem, and Thap Khang.

There are a further seven tambon administrative organizations (TAO) responsible for the non-municipal area.