at
Silverstone in 2019 Gunn began his racing career in karting at the age of eight, winning the
British Super One MiniMax Championship in 2011 before taking the
British Super One Junior Rotax Championship title the following year. In 2013, he graduated to single-seater formula competition, competing in the
BRDC Formula 4 series. However, he was forced to miss the final two rounds of the season due to a lack of funding. Scoring two race victories, Gunn finished 11th in the championship. As a result of his lack of funding, Gunn wouldn't race competitively in 2014, but would return in 2015 by taking part in the
Aston Martin Evolution Academy. That season, Gunn and co-driver
Jamie Chadwick secured the
British GT Championship GT4-class title, driving for
Beechdean-
AMR. In December, Gunn was announced as the winner of the
Aston Martin Evolution Academy, which lead to his signing as an
Aston Martin factory driver for 2016. After a year of GT3 competition in 2016, Gunn stepped up to the
GTE ranks with
Beechdean-
AMR, competing in the
2017 European Le Mans Series. In 2019, Gunn secured his first full-time
FIA World Endurance Championship ride with
Aston Martin Racing's GTE Am class entry, driving alongside
Paul Dalla Lana and
Darren Turner. The team would collect four podium finishes in eight races, finishing seventh in the championship. 2021 saw Gunn join
Aston Martin customer team Heart of Racing in the
IMSA SportsCar Championship. Following the
12 Hours of Sebring, Gunn was confirmed as the full-season partner for Roman de Angelis, with team boss Ian James set to step back to the series' endurance events at
Watkins Glen and
Road Atlanta. That season, the duo claimed the WeatherTech Sprint Cup title, awarded to the highest performing team throughout the season's sprint events. Gunn was victorious in the final race of the season at Petit Le Mans, held at Road Atlanta. 2022 saw Gunn join the team's GTD Pro class entry, paired for the season with Alex Riberas. After a difficult start to the season, featuring retirements at both
Daytona and
Sebring, the duo scored class victories at
Long Beach and Watkins Glen, rebounding to finish fourth in the GTD Pro championship. Gunn returned to the team for the following season. in 2025 In 2023, Gunn returned to the
British GT Championship, reuniting with Andrew Howard and the
Beechdean AMR team. He would make it three full-time programs for 2023 following the announcement of
TRG's
GT World Challenge America entry, where he partnered with Derek DeBoer. As the team's factory representative, Gunn primarily played the role of initially bringing the team to terms with the
Aston Martin Vantage AMR GT3 and coaching DeBoer. Furthermore, he cited his IMSA factory drive as taking the highest priority, as his three-pronged program encountered several conflicting race dates. ==Racing record==