After proving himself with the Raiders Premier League squad and with strong appearances for the junior Queensland and Australian sides, Zillman was rewarded with his first NRL appearance early in the 2006 season. His first grade debut in the National Rugby League was against the Newcastle Knights in round 2 of 2006 at Canberra Stadium. At 19 years of age Zillman was named in the starting squad at fullback and although scoring two tries on debut the Raiders went down 70-32 in a record-breaking heavy defeat by Newcastle. Coach at the time Matthew Elliott named Zillman on the bench for round 4 and round 5 of the 2006 season, but Zillman played the remainder of the season back in Premier League as he was stuck behind Canberra's first-choice full-back Clinton Schifcofske, who was the current captain at the time and a Queensland State of Origin representative. In credit to Zillman, Schifcofske had a stellar year winning the Dally M Fullback of the Year which didn't help Zillman break into first grade. The young Queenslander didn't let this set-back get in the way of his rugby as he shone as a stand-out player in the Premier League amassing 17 tries in the season and securing another Australian jersey through selection in the 2006 Junior Kangaroos. When Shifcofske announced during the middle of the 2006 season he had made the decision to switch codes to sign with rugby union club the Queensland Reds for the 2007 season, the opportunity to once-again play in the NRL arose.