Oka is a surname. Notable people with the surname include:
Arsene Oka (born 1983), Côte d'Ivoire football (soccer) playerAsajiro Oka (丘浅次郎 Oka Asajirō, 1866–1944), Japanese zoologist, anatomist and evolutionistAyumi Oka (born 1983), Japanese actressAyumi Oka (born 1986), Japanese female tennis playerGedong Bagus Oka (1921–2002), Hindu reformer and philosopher in IndonesiaKazuo Oka (born 1948), Japanese voice actorKiyoshi Oka (1901–1978), Japanese mathematicianMasi Oka (born 1974), Japanese American actor and digital effects artistTakeshi Oka (born 1932), Japanese-American chemist and astronomer