Girdler first played in the New South Wales Rugby League for the Illawarra Steelers in 1991, playing his first game from the bench in a 26–14 win over South Sydney at the Wollongong Showground. During his time at Illawarra, he struggled with injuries and with the likes of Paul McGregor and Brett Rodwell cemented as the Steelers centre pairing, received few chances to reach his full potential. As a result, he usually found himself playing on the for the Steelers, though in 1992, his form saw him play 20 games for Illawarra (12 in the centres) and take over the goal kicking duties from Rod Wishart. Girdler was the Steelers top point scorer in 1992, scoring 118 points from 8 tries and 43 goals from 66 attempts (65.15%)