As his career seemed to be in a deadlock after a difficult 2014 season, with him being forced to work as a car cleaner for a time, Gounon took part in the "Espoir Porsche Carrera Cup France 2015" scholarship thanks to a 1,500€ gift from his grandfather; he ended up winning the shootout to take part in Porsche Carrera Cup France for the next season with a grant of €30,000.

However, Jules Gounon suffered a big crash at Hockenheim, staying conscious and alert, but with an injured (although not broken) left leg.

[12] After this round, his teammate Keilwitz got injured and was replaced by Renger van der Zande who won with Gounon in Zandvoort, letting the Frenchman take alone the championship's lead.

After two complicated races, the Frenchman set the fastest time of the qualifying session in Paul Ricard, faster than his teammates and than his rivals.

[24] Battling with the Ferrari 488 GT3 of Miguel Molina, Jules Gounon and Bentley won their first race of the year and also their first win since the introduction of their new car back in 2018.

[25] Two weeks later, Jules Gounon participated in his first 24 Hours of Le Mans with Risi Competizione, teaming up with Oliver Jarvis and Pipo Derani on a Ferrari 488 GTE Evo.

[27] 2021 would see Gounon become a works driver for the Mercedes team, as he took part in the GT World Challenge Europe Endurance Cup with Daniel Juncadella and Raffaele Marciello.

[28] A strong start with a podium in Monza and a sixth place in Le Castellet was followed by disappointment at Spa, where the outfit was forced to retire, having previously taken pole position.

[40] The season would contain campaigns in three championships: the GTWC Europe Endurance Cup, where Gounon and Marciello would attempt to defend their title alongside Timur Boguslavskiy, the GTD Pro class in IMSA, which the Frenchman contested alongside Juncadella for WeatherTech Racing, and the British GT Championship as Ian Loggie's teammate.

[41][42][43] Despite a retirement in the Endurance Cup season opener at Monza, Gounon would be able to retain the title, with wins at Le Castellet and the Nürburgring sandwiching a runner-up finish at the 24 Hours of Spa.

[44][45][46][47] Over in America, Gounon, together with Juncadella, Maro Engel and Cooper MacNeil, won the 24 Hours of Daytona at the start of the year.

[48] Gounon and Juncadella combined for a further three victories that season, including a triumph at the season-ending Petit Le Mans race, which earned them second in the drivers' standings and the title in the Michelin Endurance Cup.

[49] The British series proved to be less fruitful, as the Frenchman scored a lone win at Oulton Park and finished sixth in the drivers' championship, having missed one race.

With a victory at Bathurst, third places at Kyalami and Abu Dhabi and runner-up finishes in Spa and Indianapolis, the Frenchman would clinch the title, having completed a podium sweep whilst racing with four different Mercedes-affiliated teams.