Khao Chamao (Thai: เขาชะเมา, pronounced [kʰǎw t͡ɕʰā.māw]) is a district (amphoe) of Rayong province, eastern Thailand.

[2] With publication in the Royal Gazette on 24 August the upgrade became official.

[3] Neighboring districts are (from the north clockwise) Bo Thong of Chonburi province, Kaeng Hang Maeo of Chanthaburi province, and Klaeng and Wang Chan of Rayong Province.

The district is divided into four sub-districts (tambons), which are further subdivided into 21 villages (mubans).

There are no municipal (thesabans), but there are four tambon administrative organizations (TAO).