Hibernian attempted to sign Robertson as a teenager but he asked for time to think the deal over; after Hibs refused, he signed for Heart of Midlothian along with school friend and fellow future internationalist Dave Bowman. Robertson eventually earned the moniker "The Hammer of Hibs" (in addition to his more standard nickname "Robbo") as he scored a record 27 goals in Edinburgh derby matches. In 1986, 20 league goals from Robertson helped Hearts to the brink of a league and cup double. A 27 league game unbeaten run ended with two Albert Kidd goals for Dundee in the last six minutes of the season allowing Celtic to overtake them to win the title. A week later, Hearts lost 3–0 to Aberdeen in the cup final. He scored 106 goals in 202 Hearts league games in this spell at Tynecastle Park.