Jahn made his car racing debut in 2009, racing in the ADAC Volkswagen Polo Cup, in which he won at
Barcelona and finished seventh in points. The following year, Jahn raced in the Porsche Super Sports Cup Germany, scoring a win at the
Hockenheimring and ending the year fourth in points. Jahn then competed part-time in
Porsche Carrera Cup Germany across the next two years, before joining Farnbacher Racing to compete in the last four rounds of the
2013 ADAC GT Masters season. In 2014, Jahn joined Callaway-affiliated RWT Racing for his maiden full season in
ADAC GT Masters alongside
Sven Barth. Racing in all but one rounds, the pair scored their first podium at
Slovakia Ring by finishing third in race one, before then scoring their only win of the season at the
Nürburgring in race one en route to a 17th-place points finish. During 2014, Jahn also drove for RWT in the final round of the
GT Sprint Series in
Baku. at the
2015 24 Hours of Nürburgring. After only racing at the
24 Hours of Nürburgring in 2015 for
Scuderia Cameron Glickenhaus, Jahn joined Porsche-fielding
KÜS Team75 Bernhard in 2016 for his sophomore season in
ADAC GT Masters. Partnering a number of drivers including
Kévin Estre, Jahn scored victory at the
Red Bull Ring, then won at the
Nürburgring and
Zandvoort, and ended the season with another win at
Hockenheimring to secure runner-up honours in points. During 2016, Jahn also made a one-off appearance in the
Le Castellet round of the
European Le Mans Series in the GTE class for
Proton Competition. Having only made one-off appearances in
Porsche Carrera Cup cars for two years, Jahn returned to RWT Racing's Corvette for the
2019 ADAC GT Masters season. In his reunion with
Sven Barth, Jahn scored podiums at
Most and
Red Bull Ring as he ended the year seventh in points. Returning to
KÜS Team75 Bernhard for the 2020 season, Jahn guided rookie
Jannes Fittje to a best result of fourth twice and finished the season 17th in the overall standings. Switching to fellow Porsche customer Team Joos Sportwagentechnik for 2021, Jahn scored a best result of sixth twice en route to a 15th-place points finish at season's end. during the 2023
ADAC GT4 Germany. Jahn then joined W&S Motorsport to race in the new-for-2022
Porsche Endurance Trophy Nürburgring Cup. Competing in the last six races of the season, Jahn took five class wins and helped the team secure the Cup2 title at season's end. Remaining with W&S Motorsport for 2023, Jahn joined
Jannes Fittje to compete in
ADAC GT4 Germany. In his only season in the series, Jahn won at
Zandvoort and
Hockenheimring as well as taking three more podiums to end the year third in points. Continuing with W&S Motorsport for 2024, Jahn returned to
Porsche Endurance Trophy Nürburgring Cup's Cup2 class full-time, in which he scored two class wins and finished runner-up in points. Staying in the series for 2025 but switching to
Mühlner Motorsport, Jahn won all but three races to secure the Cup2 Pro title at the end of the year. In 2026, Jahn returned to
GT3 competition as he joined BMW-affiliated Gamota Racing to compete in the SP9 Pro-Am class of the
Nürburgring Langstrecken-Serie. At the 24h Nürburgring Qualifiers, Jahn took pole position, clearing the field by two seconds and beating four-time
Formula One world champion
Max Verstappen. == Karting record ==