Gerloff began competing in the Western Eastern Roadracing Association (WERA) in 2007, and by 2010 and 2011 was finishing first and second overall in the Superbike and Superstock categories on a Yamaha 600. He stepped up to the AMA Daytona Sportbike Championship in 2011 and 2012, competing nationally from 2013, where he finished third that year and sixth in 2014.
When MotoAmerica replaced the national road racing series, Gerloff joined the MotoAmerica Supersport class in 2015 and finished third in his debut season. He won the Supersport championship in both 2016 and 2017, establishing himself as the top American talent of his generation.
Gerloff's Supersport titles earned him a factory Yamaha seat in the MotoAmerica Superbike Championship for 2018. He ended that season with five podiums and fifth overall in the standings. In 2019 he claimed his first Superbike win at Laguna Seca on July 14, and went on to take four wins and eleven podiums from twenty races, finishing third in the championship behind Cameron Beaubier and Toni Elias by 51 points.
Gerloff's MotoAmerica performances earned him a move to the factory-supported GRT Yamaha WorldSBK Junior Team for the 2020 Superbike World Championship. He took two third-place finishes at Catalunya and Estoril and ended the year eleventh with 103 points.
In 2021, Gerloff made further progress and signed a further contract with GRT Yamaha for 2022. He recorded no wins but increased his podium tally and was a consistent top-five contender throughout much of 2021, though he attracted controversy after crashing into factory Yamaha rider Toprak Razgatlioglu at Assen. His results helped GRT Yamaha clinch the Independent Team's Championship, while Gerloff himself won the Independent Rider's Championship as the highest-scoring non-factory rider.
From the 2023 season, Gerloff joined the Bonovo Action BMW Team, switching manufacturer for the first time in his World Superbike career.
Gerloff came close to a MotoGP debut in November 2020 when he was announced as a replacement for Valentino Rossi — who was recovering from COVID-19 — at the European Grand Prix. Gerloff completed Friday free practice sessions before Rossi returned following a negative test on Saturday, and Gerloff was withdrawn from the race weekend.
He ultimately made his MotoGP race debut at the 2021 Dutch TT, filling in for the injured Franco Morbidelli at the Sepang Racing Yamaha team. Gerloff rode the older 2019 A-Spec YZR-M1 rather than the current-specification machine and finished seventeenth. The outing made him the first American to compete in the premier class since his idol Nicky Hayden's final race in 2016.
Gerloff represents a rare modern example of an American rider bridging domestic success in MotoAmerica to both World Superbike and MotoGP competition. His Independent Rider's Championship in 2021 confirmed his standing as one of the stronger non-factory talents in WorldSBK, and his pivot to BMW with Bonovo Action signaled ambitions for a factory-level ride. He remains one of the most prominent American figures in international road racing since the Hayden era.