Liverpool born outside left Jack Casey began his football career with Bromley, from where he joined Southern League club West Ham United in the close seasons of 1912, making his debut against Gillingham on 2nd November 1912. West Ham began a good run of form in January 1913 and a team that included Casey, George Hilsdon, Dan Bailey, Fred Harrison, George Butcher, Herbert Ashton and Bert Denyer, went through the rest of the season unbeaten. This included 7 matches won and 8 games drawn.
Casey ended up his breakthrough season with 3 goals in 28 matches, and continued playing regularly in the final two seasons before the onset of the First World War forced the suspension of peacetime football in May 1915, by when Casey had scored 13 goals in 83 appearances for The Hammers. Casey continued to appear regularly in wartime league football until his final match in October 1917, scoring a further 6 goals in 30 wartime matches. He also made one guest appearance in a friendly for Tottenham Hotspur against West Ham United in May 1917 when Tottenham arrived two players short fielding two West Ham players to make up the shortfall, and after the War he joined Clapton Orient in the summer of 1919. However he never managed to break into their first eleven before his eventual retirement.