Welton, Yorkshire born goalkeeper Walter Cook began his football career in local league football in the West Riding area, and during the First World War made 11 appearances for Leeds City in 1918 as a ‘guest’ player. Following Leeds City’s expulsion from the Football League due to financial irregularities in the early stages of the 1919-20 season, he was released without having played a League game, and signed for Castleford Town. It was for Castleford that he made his senior debut in a first round proper FA Cup tie against Hednesford Town in January 1920, Cook keeping a clean sheet in a 2-0 win.
He then joined Plymouth Argyle in the latter stages of 1921 as understudy to Fred Craig, making his Football League debut in a 3-1 win over Swansea Town on New Year’s Eve. Cook found the redoubtable Craig very reliable and made just six appearences in Argyle’s second League season and just one in the following campaign before leaving to join Brighton & Hove Albion in the summer of 1924, where he featured as their principal goalkeeper in 1924-25 before losing his place in October 1925 making only 10 more appearances during his second season before leaving in the summer of 1926 after having made 55 appearances for The Seagulls. After a trial with Darlington he subsequently made 11 appearances for Stockport County in November and December 1928 before joining non league Harrogate in 1929.