Edinburgh born inside right Billy (also known as Willie) Cowan played junior football before the First World War with Dalkeith Thistle in 1913 and Tranent Juniors in 1914 and joined Dundee after the War in January 1920, where he made his Scottish League debut in a defeat at Kilmarnock that March, scoring 14 goals for The Dark Blues in 79 appearances over the next three seasons. From there he signed for Newcastle United in July 1923, making his Football League debut against Sheffield United in September 1923. He went on to score 28 goals in 101 games over the next two years and won the 1924 FA Cup Final with The Geordies against Aston Villa at Wembley Stadium.
He was also picked for Scotland scoring against England in April of that year in a 1-1 draw at Wembley in what proved his only cap for his country within a fortnight of the Cup Final triumph. In May 1926 he joined Second Division Manchester City and scored 11 goals in 23 games during 1926-27 as they missed out on promotion finishing third, however he thereafter dropped out of the top leagues returning to Scotland to join St Mirren in May 1927, where he scored 4 goals in 10 appearances, and after spells at non league Peebles Rovers and Harrogate in 1928, and with Northfleet and North Shields in 1929, he returned to League action with Hartlepools United in September 1930 scoring twice in 3 appearances, and then joined Darlington a month later scoring once in 8 appearances, before finishing his career at Bath City in 1931 and Wolviston St Peter’s in 1933.