Robertson played junior football with Valley Dragons in the ACT, and was graded to the Canberra Raiders, making his first-grade début in 2001 against the North Queensland Cowboys.

Normally a left side winger, suspension and injuries to Brett Stewart saw Robertson play most of the 2009 NRL season at fullback for the Sea Eagles.

Robertson would fulfill a long-held ambition to play in England when he would join the Super League club the London Broncos in 2012.

[9] Due to his Scottish heritage, Robertson made himself available for Scotland's 2008 Rugby League World Cup campaign.

[10][11][12] Robertson was named in the Scotland squad for the World Cup and played all three of their games at fullback, scoring a try in the team's 18–16 win over Fiji at Bluetongue Stadium in Gosford.