He made his karting debut in 2020, coming 7th in the Trofeo Italiano Easykart, in the Easykart 60 category. For the 2022 season, he raced for Forza Racing in the OK Junior category, coming 12th in the 50° Trofeo delle Industrie, and making his debut in the CIK-FIA World Championship, coming in 26th place.
After winning the Richard Mille Young Talent Shootout, Colnaghi was announced to be making his single-seater debut in the 2024 F4 Spanish Championship with MP Motorsport.[2] Targeting top rookie honours for the campaign,[3] he experienced a difficult start to the season in with only an eighth place, despite scoring his first pole in the third race.[4] He secured his first wins in the category with a double in Paul Ricard.[5] Although Colnaghi would not win in the next two rounds, he would score double podiums which allowed him to maintain his title charge alive. This would be followed by an outstanding four wins in the next five races in Jerez and Barcelona, allowing him to take the championship lead from longtime leader Keanu Al Azhari heading into the final race.[6][7] Finishing fifth in the final race, Colnaghi was able to clinch the title, ten points ahead of Al Azhari.[8] He became the first rookie to win the Spanish F4 championship since Nikola Tsolov, who won in 2022.[9]
