Soomer began racing in the ADAC Minibike Cup in 2006, making his debut at the Sachsenring at just eight years old. He raced in the championship from 2008 to 2010, claiming a race win in 2009 and finishing as runner-up in 2010. He transitioned to the ADAC Junior Cup in 2011 and 2012 aboard an Aprilia RS125, securing a podium finish in 2012. In 2013 he entered the European Junior Cup — a one-make feeder series running alongside Superbike World Championship rounds — and remained in that championship through 2016, earning two race wins at Assen and Misano before moving across to the Supersport World Championship with Kallio Racing.
Soomer made his WorldSSP debut in 2015 as a wildcard for Kallio Racing at Magny-Cours. He took part in further wildcard appearances in 2016 before joining the European Supersport Cup full-time with WILSport Racedays in 2017, winning the Cup at Jerez. In 2018 he graduated to the full WorldSSP calendar with Racedays, finishing sixteenth with a best result of seventh at Estoril. He repeated that best result in 2019 while climbing to fourteenth in the standings.
For 2020, Soomer moved to Kallio Racing on a Yamaha YZF-R6, delivering a breakthrough campaign. He earned three podium finishes — two at Magny-Cours and one at Estoril — and closed the season ninth in the championship. He remained with Kallio in 2021, finishing twelfth despite missing two rounds due to a leg injury. In 2022 he switched to the Dynavolt Triumph team alongside Stefano Manzi, recording a best result of fifth in Race 2 at Assen and finishing thirteenth overall.
In 2023, Soomer was called up by the Petronas MIE Honda team as a stand-in for Hafizh Syahrin at the Czech and French rounds, gaining WorldSBK experience for the first time. His stand-in role in the premier class returned in 2026 when he was set to deputise for Danilo Petrucci at the Aragón round while Petrucci recovered from injury.
Soomer pivoted toward Superbike competition from 2023, racing in the IDM Superbike championship with Honda. He took five podiums across the first three rounds and finished fourth in the standings with 185 points. In 2024 he switched to BMW machinery and improved further, claiming his first IDM race victory at the Nürburgring in a battle with Illia Mykhalchyk. Injury prevented him from contesting the final round at Hockenheim after a crash at the Bol d'Or. In 2025, now part of the factory-backed Masteroil Alpha Van Zon BMW squad, he won races at Oschersleben and Most — the latter by just 0.059 seconds over Florian Alt — and finished the season third with 177.5 points. He continued with the same team in 2026 when the IDM transitioned into the EuroMoto Series.
Alongside his circuit racing, Soomer built a strong endurance record. In 2024 he raced for Tecmas-MRP-BMW at the 24 Hours of Le Mans before injury ended his outing early, then went on to win the Suzuka 8 Hours Superstock class with the TONE RT SYNCEDGE 4413 BMW team. At the Bol d'Or that year, a highside crash fractured his upper arm and dislocated his shoulder while running with the BMW factory team. In 2025 he won the Spa 8 Hours and the Bol d'Or both in the Superstock class with Tecmas alongside Jan Bühn and Leandro Mercado, demonstrating consistent endurance pace to complement his sprint-racing ability.
Soomer has established himself as one of the most versatile motorcycle racers of his generation, transitioning from Supersport to Superbike and endurance formats at an elite level while becoming a consistent race-winner in the IDM and EuroMoto arenas. His career represents an important chapter in the development of Baltic motorsport on the world stage.