Kaamatan or Pesta Kaamatan is a form of harvest festival celebrated annually in the state of Sabah in Malaysia. It is normally celebrated by the ethnic Kadazan-Dusuns, as well as by other related ethnic groups in the state, and lasts for the whole of the month of May, ending with a public holiday on a date selected by a priestess known as the bobohizan.

A beauty pageant known as Unduk Ngadau will be held and it ends the harvest festival with a newly crowned Unduk Ngadau in the annual host district, Penampang. The Harvest Festival comes under the ambit of what is known as Momolianism, the belief system and life philosophy of the Kadazan-Dusun. There is also a dance performance called the Sumazau, a singing contest called Sugandoi, a bodybuilding competition, and other arts and crafts performances. Competitions such as hitting the gong and folk sports have also become one of the main events in this festival.

Popular drinks during the festival are tapai and Kinomol, which is a traditional alak drink. Tapai is drunk from a small bamboo vessel known as a sumbiling or from special glasses called singgarung, likewise made from bamboo.