OSU can stand for:
- Institutions of higher education:
- Ohio State University
- Oregon State University
- Oklahoma State University
- Oswego State University (formerly State University of New York (SUNY) at Oswego)
- The Order of St. Ursula or Ursulines (Roman Catholic Christian religious order)
- Osu, Accra, a district in Ghana
- Igbo culture:
- Osu caste system, a caste system practiced by the Igbo people in West Africa
- Operation Straight Up, an evangelical organization that provides faith-based entertainment to the United States military
- Japanese culture:
- Ōsu, district of Nagoya
- Osu!! Karate Bu (manga)
- Osu! Tatakae! Ouendan (Nintendo rhythm game)
- osu! (a freeware clone of Osu! Tatakae! Ouendan)
- Japanese for "Patience with myself and others" used in karate
- Also used in JIKC, Kyokushin where it means "to push and to endure," a shortening of the words "oshi shinobu," and Wado-ryu Karate.