As an amateur, Pownceby was one of the New Zealand team's main hopes for a boxing medal in the 2006 Melbourne Commonwealth games[2] but he was eliminated from the competition after losing 6–26 against his first opponent.
[4] Pownceby was also selected for the 2004 Athens Olympics and was the only boxer chosen to represent New Zealand at this event.
Pownceby defeated Joel Casey for the World Boxing Foundation light-heavyweight title on 17 June 2010.
[7] Pownceby has also held the WBO Asia Pacific light-heavyweight title after defeating Togasilamai Letoa in a 12-round fight.
His father (a United States Navy serviceman) has never acknowledged him, his sister was murdered by her partner in 1990, and his mother died of cancer in 1993.