Dew made his debut with the Port Adelaide Football Club in 1997, their inaugural year in the AFL. But it was not until the 1998 season that he received regular selection. He was occasionally criticised[who?] for his lack of dedication on the training track; however, as he matured, Dew became an important player for the Power as evidenced during the 2004 season when he kicked 31 goals and was a part of the club's premiership win. The 2005 season saw Dew play a running half-back role and played in all 24 games. He complemented Port recruit Nathan Lonie, in that they played similar roles. On 6 November 2006, Dew announced his retirement from the AFL.
Despite not playing football at any level during 2007, Dew announced his intentions to come out of retirement to pursue an AFL career again. He nominated himself for the 2007 AFL National Draft and was selected by Hawthorn with its third round selection (No. 45 overall). He debuted for Hawthorn against Melbourne in round 1 2008, and injured his hamstring in his second match against Fremantle. He missed some games later in the year by injuring his hamstring again but was fit and playing good footy by the time of the finals. Stuart repaid the faith shown in him with a brilliant burst in the Grand Final when the result was still in the balance in the third quarter, kicking two goals and setting up two others. A series of soft tissues injuries restricted Dew to 11 games in 2009 and he announced his retirement from AFL at the end of the 2009 season.