Burnhope, County Durham born outside right Walter Coates joined junior club Burnhope in 1912, playing for Craghead United in 1913 and Sacriston United in 1914 before the First World War, during which he played Army football before joining Second Division Fulham after the War in August 1919, making his Football League debut at Leicester City in September 1919. He made one further first team appearance two days later in a home win over Clapton Orient but failed to break through into the Fulham first team during the rest of 1919-20 before he returned to County Durham, joining North Eastern League side Leadgate Park in July 1920.
He moved to Leeds United a year later, but after 20 appearances in his debut season he only made the team once in 1922-23. He made 21 appearances in the campaign as they won the Second Division Championship in 1923-24, Coates scored the goal which beat Nelson in the penultimate game of the season to give Leeds the Second Division title. However he made only 8 appearances the following season in the First Division before joining Newport County in July 1925 after 4 goals in 50 appearances for the Elland Road club.
He stayed a single season in Wales scoring 7 goals in 26 games before joining Irish League Linfield in 1926, before returning to Football League action with Hartlepools United in August 1928, making 2 first team appearances at Victoria Park that September, suffering a knee injury before joining non league Chester-le-Street in 1929. He subsequently moved to Newport (Isle of Wight) in 1930, before playing for Burnhope Institute in 1931 and Consett in 1932.