Gilbert played up to the age of eleven football, but then changed the sport. In 1986, he was both in single as well as double the national French tennis champion. Two years later he became a professional tennis player, first played on the ATP Challenger Tour, where in Hossegor he celebrated his first title victory in 1990. The following year he won another Challenger Title in Neu-Ulm, also he could with his compatriot Olivier Delaitre win his first doubles title on the ATP World Tour. Between 1993 and 1995 he won more titles on the Challenger tour, followed in Johannesburg his second and final ATP doubles titles. A further two times he was in the course of his career in a double finals. Its highest listing in the tennis world ranking he reached in 1992 with position 61 in the singles and in 1996 with position 50 in doubles.
His best individual result at a Grand Slam tournament was the two-time reaching the third round at the French Open, where he was successful against Boris Becker in 1993. In doubles, he reached the knockout stages once each at the French Open and the U.S. Open.
Gilbert played a single game in 1993 for the French Davis Cup team. In the semifinals of the World Group, which went 2-3 lost to India, he took up in singles against Ramesh Krishnan, but lost in five sets.