From 1988, Campbell represented New Zealand in various international amateur competitions, including the team victory at the 1992 Eisenhower Trophy, before turning professional in 1993. Two years later, in his first full season on the European Tour, he held a two-shot lead after the third round of The Open Championship, but faded after a final-round 76. He nonetheless remained in contention until the final hole, missing a playoff with Costantino Rocca and John Daly (eventually won by Daly) by one stroke.