Gené began competing in karting as a child, winning both the Catalan and Spanish Kart Championship National Class titles in 1988 and becoming the youngest driver to win the Senior Class of the Spanish championship in 1990. He moved into car racing with Formula Ford in 1992, placing fifth in the Spanish championship, and was runner-up in the 1993 European Formula Ford Championship. Named Rookie of the Year in the 1994 British Formula Three Championship, Gené went on to win the FISA Superformula title in 1996. A brief appearance in FIA Formula 3000 in 1997 yielded no points, but victory in the 1998 Open Fortuna by Nissan Championship — with six wins and three pole positions — elevated him into Formula One contention.
In 1999, Gené secured a race seat with Minardi. In an otherwise difficult season, he achieved the team's first points finish since 1995 with a sixth place at the European Grand Prix, a result that required navigating through the attrition of one of the most chaotic races of the season. He continued with Minardi in 2000 but failed to score, his best finish being eighth at the Australian and Austrian Grands Prix.
Unable to secure a competitive race drive for 2001, Gené joined Williams as a test driver, a role that would occasionally put him in a race seat as a substitute. His most prominent stand-in race came at the 2003 Italian Grand Prix, where he replaced an injured Ralf Schumacher and finished fifth, collecting four championship points. The following year, following Schumacher's back injury at the 2004 United States Grand Prix, Gené drove for Williams at the French and British Grands Prix before the seat was taken by Antônio Pizzonia.
In November 2004, Gené signed with Scuderia Ferrari as a test driver alongside former teammate Luca Badoer. His contract was renewed for 2007. Reduced testing regulations across the 2007 and 2008 seasons limited his track time, and at the end of 2010 he was replaced by Jules Bianchi as Ferrari's test driver heading into the 2011 season.
Peugeot engaged Gené as a factory driver for its Le Mans programme from 2007. In 2008 he suffered a heavy crash during practice for the 24 Hours of Le Mans, escaping with only a broken toe. The following year proved far more successful: co-driving a Peugeot 908 HDi FAP alongside David Brabham and Alex Wurz, Gené's crew completed 382 laps to win the 2009 24 Hours of Le Mans, ending Audi's recent dominance of the event. Gené drove the final stint, bringing the car home to a standing ovation from the crowd. He also won the 1000 km of Spa in 2008 with Peugeot.
Starting from the 2010 Formula One season, Gené moved into television commentary, covering Formula One races for Spanish broadcaster Antena 3. In 2013 he became an expert analyst for Sky Sport F1 HD in Italy. He has continued in these media roles while maintaining his position as a Ferrari brand ambassador, bridging his technical and competitive experience with a broadcasting career that has made him one of the most recognisable Spanish voices in motorsport.