In October 2009, Robertson clinched the 2009 Grand Prix trophy in Glasgow with a 9–4 win over China's Ding Junhui in the final. His semi-final match with defending champion John Higgins was won on the final black of the deciding frame. Robertson's fourth title made him the most successful player from outside the UK and Ireland in ranking tournaments, although Ding Junhui equalled his total at that season's UK Championship. He achieved his 100th career century during the 2009 Grand Prix.