Powell started playing rugby at the age of 10 for Brecon Rugby Club as a centre. He has been a member of the Cardiff Blues squad since 2005. The back row forward joined from the Llanelli Scarlets and has previously played for Beziers, Leicester Tigers and Newport. Powell is a former Wales U21 and Wales A player.

He sustained an injury to his right shoulder in April 2006 and had shoulder reconstruction surgery at the start of the 2006 season and was out for the majority of the season. He made a comeback in April 2007, but sustained another shoulder injury, to the left this time, before the close of the season. He underwent major shoulder surgery for the second time in a matter of months, which meant he would miss the start of the 2007 season.

Powell flourished at the beginning of the 2008 season which he began as the first choice No8 in the Blues squad. He produced eye catching performances in both the EDF Challenge Cup and Heineken Cup. Wales coach Warren Gatland went as far as describing his efforts as ‘world class.’

Powell followed those displays with further block busting performances for Wales in the autumn to gain further plaudits which he carried through to the 2009 RBS 6 Nations.