Lecuona made his Moto2 World Championship debut in 2016 as a replacement for the injured Dominique Aegerter at CarXpert Interwetten. The following season with Garage Plus Interwetten was disrupted by serious back and collarbone injuries sustained in pre-season testing at Jerez, causing him to miss the opening two rounds, though he did score his first world championship points late in the year.
His breakthrough in Moto2 came in 2018 with Swiss Innovative Investors. At the season finale — the Valencian Community Grand Prix — Lecuona finished second behind KTM rider Miguel Oliveira, claiming his first world championship podium. He accumulated ten other points-scoring finishes and ended the season twelfth in the championship standings.
In 2019 with the American Racing team, Lecuona secured a second Moto2 podium: third place at the Thailand Grand Prix behind Brad Binder and Luca Marini. That result, combined with his prior performances, was sufficient to earn promotion to MotoGP for 2020.
Lecuona made his MotoGP debut at the 2019 Valencia season finale as a substitute for Miguel Oliveira at Tech3, retiring after a crash on lap 13. He was then signed as a full-season Tech3 KTM rider for 2020, following the departure of Johann Zarco.
His rookie MotoGP season in 2020 was limited by the COVID-19 pandemic. He scored points in seven races and recorded three top-ten finishes — ninth at Aragón and Austria, tenth in Styria — before the season was further disrupted when mandatory quarantine rules related to COVID-19 contacts forced him to miss the European Grand Prix. He also tested positive for the virus himself, causing him to miss both the Valencian Grand Prix and the Portuguese Grand Prix.
In 2021 Lecuona remained at Tech3 alongside new teammate Danilo Petrucci. The season proved to be his last in MotoGP: Tech3's 2022 seats went to Remy Gardner and Raúl Fernández, who had dominated the 2021 Moto2 championship, and Lecuona was left without a MotoGP ride.
Lecuona secured a place in the Honda Racing Corporation factory Superbike team for the 2022 Superbike World Championship, replacing the departing Álvaro Bautista. He spent four seasons with Honda on the CBR1000RR-R, establishing himself in the series against the dominant Ducati Panigale V4R machinery piloted by Bautista.
During 2023 he made two guest returns to MotoGP as a substitute rider: at the Spanish Grand Prix and Dutch TT for the Repsol Honda Team, and at five other rounds for the LCR Honda Castrol team, covering for Álex Rins at the British, Austrian, Catalan, Malaysian, and Qatar Grands Prix.
In 2026 Lecuona was selected to make a further MotoGP guest appearance, replacing Álex Márquez at the Hungarian Grand Prix for BK8 Gresini Racing MotoGP.
For the 2026 Superbike World Championship season, Lecuona joins the Aruba.it Racing Ducati team — again replacing Álvaro Bautista — returning to the manufacturer whose hardware dominates the series he will now compete on. The move ends his four-year association with Honda and places him at the centre of one of the most competitive Superbike programs.
His planned appearance at the 2025 Suzuka 8 Hours endurance race was cancelled after he sustained injuries in a multi-rider accident at the Hungarian Superbike round.