Because of his studies, he mainly played for Worksop's reserves, but in a first-team match against Northampton Town he caught the opposition's eye and they offered him a contract, leading him to turn professional for the first time in 1901. He played for Northampton for the whole 1901–02 season, finishing as top scorer with 14 goals in 22 games for the club. During that season he had impressed in an FA Cup match against Sheffield United, leading them to offer Chapman a contract at the end of the season; Chapman accepted but dropped down to amateur status, wishing to make use of his engineering qualifications in the local area. He played 22 matches and scored twice for United, but struggled to keep his place in a team full of internationals, and was sold to Notts County for £300 at the end of 1902–03. Chapman turned professional again, but only made seven appearances in two years for County, scoring once.