Walker won his first international cap for Scotland against Northern Ireland on 30th March, 1895. Walker scored two goals in Scotland's 3-1 victory. He also won two Scottish League championship medals in the 1894-95 and 1896-97 seasons.
Walker made his debut in the Football League in a 4-0 home win over Sheffield Wednesday in September 1898. That season he scored six goals as Liverpool finished runners-up in the First Division behind Aston Villa.
Walker joined Glasgow Rangers in May 1902. The following season he was a member of the Rangers' team that won the Scottish Cup. In August 1904 Walker joined Greenock Morton. He retired from football in April 1905.
John Walker died in 1940.