Osman was born in Repton, Derbyshire, the son of Rex Osman who played a handful of games for Derby County in the early 1950s. Osman played nearly 400 games for Ipswich Town, winning the 1980–81 UEFA Cup. Osman also contributed to Ipswich's victorious 1977-78 FA Cup campaign, making four appearances during the run. However he wasn't part of the squad for the final itself. Osman also represented his country 11 times. His first England cap came against Australia in a friendly on 31 May 1980, his last on 21 September 1983 in England's 1-0 Euro 84 qualifying match defeat to Denmark.