León was born in Monterrey and began competitive karting in 2013. In the off-season he trains alongside fellow Mexican drivers Pato O'Ward and Sergio Pérez. In January 2022 Red Bull announced León as a member of the Red Bull Junior Team; however, the relationship lasted only a year and he was dropped at the start of 2023. León later revealed he had not received adequate support from the programme before his first European season, and that promises to place him in a top-three team had not materialised.
León first appeared in single-seaters at the penultimate round of the 2017–18 NACAM F4 season, deputising for a teammate at Ram Racing. He finished on the podium in races one and two on debut. He returned for the opening round of the 2018–19 season supporting the Mexican Grand Prix, again podium-finishing in race one.
In the full 2019–20 NACAM F4 season with Ram Racing, León was dominant. He opened with a win and podium at the round accompanying the 2019 Mexican Grand Prix and scored a win in each of the six remaining rounds. With eight further podiums, he clinched the title with one race in hand.
For 2021 León graduated to the F4 United States Championship with DEForce Racing alongside compatriot José Andrés Martínez. He managed just two outright wins — at Road America and Mid-Ohio — but his consistency across the year, capped by a double podium at Circuit of the Americas supporting the United States Grand Prix, was enough to claim the championship.
León stepped into European racing in 2022 with the Formula Regional European Championship, driving for Arden Motorsport. His season was difficult: he failed to score in the opening two rounds at Monza and Imola, took tenth and ninth in Monaco, and added no further points, finishing 23rd overall with three points.
Switching to the Euroformula Open Championship with Team Motopark in 2023, León found his footing in European racing. He took seven victories and a further nine podiums across the season, securing the title by 87 points. His campaign included a podium on debut in Portimão, a podium lockout in Spa-Francorchamps including a race win, victories at the Hungaroring and in Austria (where he responded to a first winless weekend in Paul Ricard with a double win), and further wins in Monza and Mugello where he clinched the title with one round remaining.
León joined Van Amersfoort Racing for the 2024 FIA Formula 3 Championship. After a scoreless opening two rounds, he collected four podiums across the season — second in the Silverstone sprint, second in the Budapest feature race, and sprint race podiums at Spa-Francorchamps and one other occasion. He finished tenth in the standings with 79 points, contributing virtually all of Van Amersfoort's points that season. At the 2024 Macau Grand Prix with Pinnacle Motorsport, he ran third throughout and defended to secure a podium at the finish.
For 2025 León moved to reigning champions Prema Racing alongside McLaren juniors Ugo Ugochukwu and Brando Badoer. The team struggled to adapt to new regulations and León's season was inconsistent, marked by difficult weekends in Monaco and a broadly unproductive mid-season stretch. Highlights included a strategic wet-tyre gamble in the Silverstone feature race that brought his first podium of the year, and a front-row start converting to third in the Monza feature race. He ended the season seventeenth with 36 points and two podiums.
León was promoted to Formula 2 for 2026, joining Campos Racing alongside Red Bull junior Nikola Tsolov.