Loovens spent the 2005–06 season on loan at Championship side Cardiff City and impressed enough so that they signed the promising young defender on a permanent deal after several months of negotiations for a reported fee of £250,000. He originally formed a defensive partnership with club captain Darren Purse but the 2007–08 season saw Purse lose his place in the side to Roger Johnson and the pair went on to form a vital base for the team to build on, including playing alongside each other in all six matches during the club's run to the 2008 FA Cup Final. Loovens found the back of the net in the final against Portsmouth but it was disallowed for an earlier infringement. The 2007–08 season also saw Loovens make his 100th appearance in all competitions for Cardiff by playing against Hull City on 12 March.