Vermeersch came to the road from cyclo-cross, where he won a Belgian youth title in 2015 and took junior wins including the Flandriencross, the Zilvermeercross and the Krawatencross. He shifted his focus to the road in the under-23 ranks, winning the Belgian under-23 road race title in 2019 ahead of Gilles De Wilde. He was studying history at Ghent University when Lotto Soudal turned him professional in June 2020.
In September 2021 he took bronze in the under-23 time trial at the world championships in Flanders, eleven seconds behind Johan Price-Pejtersen. Two weeks later, at his first Paris-Roubaix, he got into the early break on a wet and muddy day, the first rain-hit edition in almost twenty years, and arrived at the velodrome with Sonny Colbrelli and Mathieu van der Poel. Colbrelli took the sprint and Vermeersch was second.
His first professional win came at the Antwerp Port Epic in 2022, and he rode the Tour de France that year and again in 2023. He won the Serenissima Gravel in 2023 and was second at the gravel world championships in Veneto that October, forty-five seconds behind Matej Mohorič, then second again in 2024 on Belgian roads in Flemish Brabant, behind Van der Poel.
That second silver came eight months after he broke his femur in a crash at the Vuelta a Murcia in February 2024, his first race of the season, an injury that cost him the cobbled classics. UAE Team Emirates announced his signing that April and he started with the team in 2025.
He finished fifth at Paris-Roubaix in his first season with the team, on the day Van der Poel won it again and his UAE leader Tadej Pogačar was second. In October he went back to the gravel world championships, run over laps of the Zuid-Limburg hills with a finish in Maastricht, and rode away alone on the eighteen-kilometre run-in to the city, taking the title by forty seconds from Frits Biesterbos, with Mohorič third.









