Cambridge born inside right Percy Humphreys joined local junior club Cambridge St Mary’s in 1897, where he represented Cambridgeshire FA twice in 1900 before joining Southern League club Queen’s Park Rangers that summer, turning professional. After a single season he signed for First Division club Notts County, making his Football League debut against Sheffield Wednesday in September 1901, scoring in a 6-1 victory. He was a regular scorer in The Magpies’ first eleven over the next six seasons, scoring hat-tricks in his debut season in a 5-3 win over Wolves in March 1902 and in a 4-0 win over Derby County in March 1907, and his consistency was rewarded by a call up to the England team in March 1903 for the international against Wales at Fratton Park. Although a reserve on that occasion, he won an England cap the next month when he played against Scotland at Bramall Lane in a 2-1 defeat. It proved his only cap although he also played once for The Football League.
After scoring 73 goals in 202 appearances for The Magpies, he joined Leicester Fosse in the summer of 1907, where he had scored 20 goals in 28 matches when First Division club Chelsea signed him for £350 in February 1908, the then maximum fee payable. He had nearly two years at Chelsea before he was signed by Tottenham Hotspur in December 1909 after 13 goals in 46 appearances for The Pensioners.
His 29 goals in 50 appearances for Spurs included the winner as they knocked former club Chelsea out of the FA Cup two months after his transfer. He then scored against Chelsea in the final match of the 1909-10 season which ensured that Chelsea were relegated instead of Spurs. In October 1911 he re-joined Leicester Fosse, adding 5 goals in 15 appearances to his previous totals for The Fossils before becoming player-manager of North Eastern League Hartlepools United in June 1912, scoring 11 goals in 28 appearances, before becoming manager of Swiss side FC Basel in 1913. In November 1914 he returned to England joining Norwich City. He later managed Alessandria in Italy between 1920 and 1922. He then coached in Switzerland in 1923.