[1] He won two National Karting Championships and the FIA Americas Award before transitioning to open wheel racing.

[citation needed] In 2018 he made his single-seater debut by competing in the 2018–19 NACAM Formula 4 Championship with Telcel RPL Racing.

[6][7] In 2021 Llarena made his debut in the IMSA SportsCar Championship[8] He competed in the LMP3 class with Performance Tech Motorsports.

[3][17][18] In 2022 he competed in the 24 Hours of Daytona with T3 Motorsport North America, driving a Lamborghini Huracán GT3 Evo in the GTD class.

[22] In 2024 he joined GRT Grasser Racing Team to compete in the GT World Challenge Europe Endurance Cup for the first time.