In 1993, Robertson turned professional. He gained his
European Tour card at his second visit to the
qualifying school in 1994. He finished in the top hundred on the
European Tour Order of Merit every season from 1995 to 2001, before he began to suffer from
clinical depression. He came back in 2004 on a medical exemption, and regained his European Tour card for the following season at qualifying school. However, he was unable to recapture the form from earlier in his career, and last played on the European Tour in 2007. Robertson's sole European Tour victory came at the 1999
Italian Open. That year he achieved his best year-end ranking on the Order of Merit when he finished in 25th place. Since leaving the tour, he has forged a successful career as a coach. Robertson is currently a high performance golf coach at the University of Stirling. ==Amateur wins==