In a career that spanned more than 20 years, Bullen played football professionally in Scotland, England, Australia, Greece and Hong Kong.

After failing to become an established player at a professional club in Scotland, Bullen moved to Australia to pursue his footballing career, playing for CYC Stanmore and Wollongong Wolves.

He played in the Hong Kong Football League for four seasons in total, moving from Kui Tan to Golden then on to South China.

After leading Dunfermline to the Scottish Cup Final, Bullen moved to English club Sheffield Wednesday on a free transfer in the summer of 2004.

During his time at Sheffield Wednesday he played in all eleven positions for the Owls,[4] including memorably in goal away at Millwall,[5] and received The Wash & Go good sport award for his efforts.

[6] In January 2008, Bullen was informed by Sheffield Wednesday manager Brian Laws that he would not have his contract renewed upon its expiry at the end of the 2007–08 season.

[7] Bullen's final appearance for Sheffield Wednesday came in a crucial relegation battle against Leicester City on the penultimate game of the season which the Owls won 3–1, an injury sustained in this game denied him an appearance for the last match of the season versus Norwich City on 4 May 2008 and a chance to play at Hillsborough for the last time.

[19] In January 2025, he would join Boston United as assistant manager to ex Sheffield Wednesday player Graham Coughlan.