Career
He plays his club football for Breaffy. He is the brother of Mayo team-mates Aidan and Conor. Seamie was man of the match in the 2013 Connacht Final against London.He was nominated for an All-Star in 2013.
O'Shea came on as a substitute in the 2012 All-Ireland Senior Football Championship Final, which Mayo lost by 0-13 to 2-11 against Donegal. In the 2013 All-Ireland final, he started at centre midfield as Mayo lost by a point to Dublin.