Lang had been playing for local Glasgow sides Co-op United and Govern when he was signed by Barnsley in August 1902. Making his Football League debut against Stockport County in September 1902, Lang stayed less than a season with the Yorkshire club, joining their local rivals Sheffield United for a £75 transfer fee in March 1903. Lang remained with United for just over five seasons but was injury prone and the 1904–05 season was the only one where he retained a regular place in the side. Despite this, he played over 100 games for the Blades before being sold to Leicester Fosse in September 1909. Leicester had paid £75 for Lang's services, but the cheque bounced and his move was delayed. Lang's stay at Leicester was only a brief one and he was released in the summer of 1910, returning to Yorkshire to work as a miner while playing non-league football for Denaby United.
