Born in La Jolla, California, Robertson has made the most of the few starring roles he has received. He has had memorable performances in PT 109 (as young John F. Kennedy), The Best Man, Charly (for which he won the Academy Award for Best Actor), Picnic and Star 80.
He is equally at home in movies and on television, and has done voiceovers for several television commercials.
Robertson has a star on the Hollywood Walk of Fame at 6801 Hollywood Blvd.