Os Turnforening is a multi-sports club from Os, Hordaland, Norway. It has sections for association football, team handball, gymnastics and track and field.
The club was founded in 1905. The football section is semi-independent and counts 1919 as its founding year.
The men's football team the club has played once, the 1975 season, in the top tier of Norwegian football, then known as the First Division. The team plays at Kuventræ Stadion and in the Third Division. It last played in the Second Division in 2010.