Stewart was mainly in double succeed where he was able to win a total of 51 titles, including the French Open in 1976 and 1982 and the Australian Open in 1984 three Grand Slam titles. In addition, he was able to reach three more Grand Slam doubles finals and finished the 1984 season together with Mark Edmondson at the top of the team standings of the tennis world rankings.
He also scored two Grand Slam successes in the mixed as well as a success in the singles at a Grand Prix event. Get him another 42 finals in a double, two in mixed doubles and one in singles. His highest placings in the tennis world ranking he reached number 60 in the single in December 1978, in a double with Rank 4 in March 1980.