 Born in Liverpool, Merseyside, Cox played for South Shore Standard, South Shore F.C., and Blackpool before being signed by Liverpool managers John McKenna and William Barclay in February 1898 for the then-large sum of £150, enabling the Lancashire club to announce a loss of "only" £441 for the season, as opposed to over £1,000 for the previous campaign.The winger made his debut on 12 March 1898, in a First Division match against Notts County at Anfield in a 2–0 win, which also saw his debut goal for the club.Cox became a regular starter for the Reds on both the left and right flanks, helping them secure their first two championships, in 1901 and 1906.