After starring for Heston Gaels GAA club at underage level, Rowlands started his football career at Wycombe Wanderers, but did not earn a professional contract and joined Farnborough Town in 1997 before moving to Brentford in August 1998 for a transfer fee of £45,000.

[2] After suffering a broken leg, Queens Park Rangers manager Ian Holloway took a gamble on Rowlands and signed him on a free transfer from local rivals Brentford in the summer of 2003.

On 25 February 2011 Rowlands signed for Millwall, on an emergency one-month loan, after only playing 23 minutes of competitive football for QPR in the 2010–11 season.

[2] Rowlands signed on a month-long contract with Leyton Orient on 28 August 2012, after spending several weeks training with the London club, and featuring in two pre-season friendly matches.

His good club form in season 2007/2008 and his subsequent player of the year awards with Queens Park Rangers led to Rowlands being included in Giovanni Trapattoni's first Republic of Ireland squad.

On 14 October 2009, he injured his anterior cruciate ligament while playing for the Republic of Ireland against Montenegro, resulting in him being ruled out of the rest of the 2009–10 season for QPR.