Robertson joined the BBC in 1972. Since April 1983 he is the Corporation's official rugby union correspondent, covering the sport not only on radio but also on television. He regards Scotland's 1984 and 1990 Grand Slams and Jonny Wilkinson's winning drop-kick in the final of the 2003 Rugby World Cup as his "best on air moments". Robertson was also a presenter of the Allied Dunbar premiership video review of 1998-1999.
Robertson is a prolific writer; he has written over 30 books and a number of autobiographies.