Hélary began karting between 1981 and 1984, then progressed through French single-seater formulae. He won the French Formula Ford title in 1988 and followed it with the French Formula Three Championship in 1990, his second year in that series. His single-seater career continued at the International Formula 3000 level before he shifted focus toward sports car and touring car racing.
Hélary first entered sports car racing via the Peugeot Spyder Cup one-make championship in 1992, winning the drivers' title in 1993. That same 1993 season he made his 24 Hours of Le Mans debut driving a factory Peugeot 905 alongside Christophe Bouchut and Geoff Brabham — and won outright on his first proper attempt. The 1993 Le Mans victory marked the culmination of Peugeot's prototype programme of that era and remains the defining result of Hélary's career.
He returned to endurance racing in 1996 in the FIA GT Championship driving a Chrysler Viper, then made a series of intermittent appearances in subsequent years: a one-off FIA GT start in 2001, a 2003 FIA Sportscar Championship race in a Pescarolo Courage-Peugeot alongside Nicolas Minassian, and a one-off 2004 Le Mans Endurance Series appearance with Pescarolo before completing a full season in that series in 2006. He subsequently served as Peugeot's official test driver for the 908 HDi FAP programme.
Hélary made his touring car debut in the French Supertourisme championship in 1994 with Opel, finishing fifth in the standings that year and improving to runner-up in 1995. He branched into ice racing during the winter of 1996 with the Trophées Andros alongside Opel, finishing fourth overall, then second overall in the 1997 edition. He spent 1997 as a test driver for BMW's Super Tourenwagen Cup team before returning to Opel in the series for 1998 and 1999. When the Deutsche Tourenwagen Masters was relaunched in 2000, Hélary competed with Opel and made one further DTM appearance in 2002. He also made a one-round World Touring Car Championship appearance in 2005 in a Peugeot 407 for Peugeot Sport Denmark.
Hélary remained active in motorsport well into his forties. He won the Euro Racecar championship in 2011 and competed in the NASCAR Whelen Euro Series Elite 1 division, demonstrating his breadth across racing disciplines.
Hélary's career follows a pattern common to French drivers of his era: a thorough grounding in national single-seater championships, a defining moment in a factory prototype at Le Mans, and a sustained multi-discipline career thereafter. His 1993 Le Mans victory with Peugeot was part of a brief but dominant chapter for French prototype racing, and it stands as the peak achievement of a driver who never pursued the Formula One path but found success in the disciplines he chose.