Centre forward Willie Porteous was a forward who could play all along the forward line. He began his senior football career when he signed for Scottish League club Heart of Midlothian in 1899, playing at outside left on his Scottish League debut in a win over Celtic at Tynecastle in November that year. Porteous made 89 appearances for Hearts over five seasons with the club, mainly at centre forward, scoring 43 goals for The Jambos, and he helped them to finish runners up in The Scottish League in 1903-04, and to win the Scottish Cup in 1901, playing inside left as they beat Celtic 4-3 in the Final at Ibrox. He also played for Hearts in the 1903 Scottish Cup Final, but they were beaten 2-0 by Rangers in the Final at Celtic Park, Glasgow.
Porteous won his only cap for Scotland when selected in a 2-0 defeat to Ireland at Celtic Park in March 1903. He was signed by Southern League club Portsmouth in 1904. He made his Southern League debut in a 2-2 draw at rivals and defending Champions Southampton in the first match of the season that September, but only spent a season at Fratton Park scoring 6 goals in 14 League and Cup appearances before returning to Scottish League football with Falkirk in 1905, his last known club before his eventual retirement.