OSB may stand for:
- Oracle Service Bus, a software component
- Order of Saint Benedict, a monastic order
- Orthodox Study Bible, an Eastern Orthodox study Bible in English, including the Septuagint
- Oregon State Bar
- Oriented strand board, an engineered wood product
- Old Saybrook (Amtrak station), Connecticut, United States; Amtrak station code OSB
- Operation Smiling Buddha, India's first nuclear test
- Orquestra Sinfônica Brasileira, the national Symphony Orchestra of Brazil, based in Theatro Municipal