Joined on loan from FC Halifax Town in October 2024. A former West Ham United and Colchester United academy player, Cosgrave earned a first taste of senior football at Essex club Coggeshall Town where he won promotion, leading to a move to newly promoted Havant in the National League in 2017. 

Following spells with Chelmsford City, Welling United and Lewes, he moved into League One with AFC Wimbledon for the 2021/22 season. While at Plough Lane, he also turned out on loan for Dover and Southend in the National League, and with National North runners-up King’s Lynn Town. 

Halifax made the move to sign him permanently at the beginning of last season and he has since featured 40 times for the Shaymen.

He scored 11 goals in all competitions in his first campaign with the Fleet.