Kern established himself early as a specialist on the Nürburgring Nordschleife, setting numerous lap records in Porsche production cars and becoming a Porsche development driver. His role bridging factory test work and customer racing gave him wide experience across the Porsche GT range before he moved into sustained IMSA competition.
Kern joined Pfaff Motorsports in 2019 for the Michelin Endurance Cup rounds of the IMSA SportsCar Championship, driving alongside Scott Hargrove and Zacharie Robichon. He scored a best result of third at Petit Le Mans.
He returned to Pfaff for the full 2020 season, paired with Dennis Olsen and Robichon in the No. 9 Porsche 911 GT3 R. Kern qualified on pole in the GTD class for the 24 Hours of Daytona, though the trio could not convert that pace into a strong result, finishing thirteenth in class. The pandemic-disrupted season limited him to two starts overall; he finished fifth at the second appearance, Petit Le Mans.
In 2021 Kern remained with Pfaff alongside Robichon and Laurens Vanthoor. He claimed his first IMSA race win at the 12 Hours of Sebring and added a second-place finish at Petit Le Mans as the team went on to win the GTD class title. That same year Kern was part of the Manthey Racing squad that won the 24 Hours of Nürburgring overall, together with Matteo Cairoli, Michael Christensen, and Kévin Estre; he was unable to race due to illness and was therefore not credited with the victory.
For 2022 Kern switched to the newly formed AWA team, contesting Michelin Endurance Cup rounds in LMP3 alongside Matt Bell, Orey Fidani, and Kuno Wittmer in the No. 13 Duqueine M30-D08. The team's best result that season was fourth at Sebring.
Kern re-signed with AWA for 2023, again sharing the car with Bell and Fidani for the Michelin Endurance Cup. The trio earned two second-place finishes, at Sebring and Petit Le Mans.
In 2024 AWA moved to the GTD class with a new Chevrolet Corvette Z06 GT3.R, and Kern moved with the team. Bell and Fidani continued as teammates. Despite a difficult season without a podium — the best result was sixth — Fidani's consistent performances earned the team the Bob Akin Award for Bronze-rated drivers, granting AWA, Kern, Bell, and Fidani an automatic invitation to the 2025 24 Hours of Le Mans.
Kern returned to AWA for 2025 with Bell and Fidani as full-time partners and Marvin Kirchhöfer joining for the 24 Hours of Daytona. Despite qualifying only sixteenth in class, the team demonstrated strong race pace and steadily advanced through the field. In the closing stages Bell battled with the No. 27 Heart of Racing Aston Martin and the No. 120 Wright Motorsports Porsche for the lead, eventually overtaking the Heart of Racing car with twenty minutes remaining. Kern, Bell, Kirchhöfer, and Fidani crossed the line first to win the 2025 24 Hours of Daytona in the GTD class.
Kern made his debut at the 24 Hours of Le Mans in 2025 as part of AWA's invitation earned via the Bob Akin Award. Sharing with Bell and Fidani, the team finished tenth in the LMGT3 class in their first Le Mans appearance.
Kern's combination of factory development work and endurance-racing experience has made him a versatile figure across the GT spectrum. His multiple Nürburgring production-car lap records reflect a distinctive skill set on technically demanding circuits, while his IMSA record — including a race win at Sebring and the 2025 Daytona GTD victory — underscores his standing in North American sportscar racing.