Walker progressed through the youth ranks at Millwall and Chelsea, and spent loan spells at Barnet, Northampton Town, Yeovil Town, Bristol Rovers and Colchester United on two occasions. He made his move to Colchester permanent in January 2014, where he made over 200 appearances. In July 2018, Walker signed a three-year contract with Reading, and joined us here at One Glove! He remained at Reading until 2021, but was loaned to Blackpool on an emergency one-week loan, which was later extended by a further week, in December 2020. In January 2021, Walker joined AFC Wimbledon on loan for the remainder of the 2020-21 season. In July 2021, Walker signed a two-year deal with Scottish Championship side Kilmarnock.