In 2021, just three weeks after he turned 15, Antonelli made his single-seater debut in the fifth round of the 2021 Italian F4 Championship, driving for Prema at the Red Bull Ring.[12][13] He got his campaign off to a good start, finishing as the best rookie in his first race and scoring four points across the weekend.[14] The Italian scored points again at the following round in Mugello, but his breakout weekend would be the final event at the Monza Circuit. Antonelli got second place in race one after a hard battle with championship leader Ollie Bearman and scored two third places to cap off the weekend.[15][16] Overall, Antonelli ended up tenth in the standings despite missing the majority of the season, being just six points behind full-time Prema driver Conrad Laursen, and finished fourth in the rookies' championship with four wins in the category.
In 2022, the Italian remained with Prema to contest the Italian F4 series, partnering Charlie Wurz, Conrad Laursen and Ferrari Academy members James Wharton and Rafael Câmara.[17] His season started out in disappointing fashion, as Antonelli was forced to retire from the season opener at Imola after a gearbox issue whilst in the lead with five laps left.[18] He would receive front wing damage after clipping a kerb in Race 2 and was penalised for a collision with teammate Wharton in Race 3, demoting him from fourth to tenth.[19] The following rounds however would bring success, with two victories at Misano, and triples at Spa-Francorchamps and Vallelunga.[20][21][22] A further win in Spielberg and Monza respectively added to Antonelli's championship advantage,[23][24] and he clinched the title by winning Race 1 at Mugello.[25] He would win the remaining two races of the season, clinching a record thirteen wins during the season.[26]
Formula 4 UAE Championship
In preparation for his main campaign in 2022, Antonelli took part in part of the Formula 4 UAE Championship. He took third place in the trophy race held in support of the 2021 Abu Dhabi Grand Prix.[27] In the main championship, he was originally set to only contest round three, but health issues for Rafael Câmara meant Antonelli replaced him in the season opener.[28] There, Antonelli took three on-the-road victories in a row, but lost the last one due to a penalty.[29] Accumulating a further podium finish in round 3, Antonelli ended up eighth in the standings despite missing over half of the season.[30]
In 2022, Antonelli raced in ADAC Formula 4 Championship in parallel with his Italian F4 programme. He took two victories in round 1 at Spa-Francorchamps[31] before completely dominating round 2 at Hockenheim, where he took all possible wins, poles and fastest laps.[32] At the third round in Zandvoort he took both pole positions and two fastest laps and took two wins in the first two races before missing out on a hat-trick of wins by 0.058 in the reverse grid Race 3 where teammate Conrad Laursen took the victory.[33] Despite missing the penultimate event at the Lausitzring, the Italian took the championship with one race to spare, having taken victory in the first two races during a weather-affected final round at the Nürburgring.[34]
Motorsport Games F4 Cup
In October 2022, it was announced Antonelli would represent Team Italy in the F4 Cup discipline of the FIA Motorsport Games.[35] He ended up winning the qualifying and main race respectively, despite racing with a broken left wrist, owing to a collision near the end of qualifying.[36] Following the win, Antonelli stated that he "had a lot of pain" and "[drove] not properly".[37]
Antonelli was confirmed to be moving into the Formula Regional European Championship, remaining with Prema for the 2023 season alongside teammates Lorenzo Fluxá and Formula 4 rival Rafael Câmara.[42] Antonelli later expressed that he was still "lacking a bit of experience, so going to F3 is a bit early for me".[43] His season started with a second place in Imola and a pair of runner-up positions in Barcelona.[44][45] A gear selection issue compromised him of a maiden FRECA win in Hungary,[46] before finally clinching victory in the second race at Spa-Francorchamps marred by the passing of Dilano van 't Hoff in a fatal accident.[47]
Wins in Paul Ricard and Mugello followed, putting him as the championship leader with breathing room to rival Martinius Stenshorne.[48][49] The seventh round in Austria saw him earn a third place podium, before winning back-to-back races in Monza, although a penalty for an illegal use of the push-to-pass system saw him lose the win in Race 1.[50][51] After winning the second race at the Zandvoort round Antonelli mathematically clinched the championship becoming the third Formula Regional European Championship by Alpine champion after Grégoire Saucy and Dino Beganovic.[52][53] Antonelli later dedicated his title to the late Van 't Hoff.[54] He secured five wins, a further six podiums and finished 39 points ahead of rival Stenshorne.
FIA Formula 2 Championship
Antonelli bypassed Formula 3 and jumped directly to Formula 2 in 2024, with Prema Racing alongside Ferrari Academy driverOliver Bearman.[55] Ahead of the season, Antonelli remarked that he "did not want to set expectations" despite early chatter of a 2025 Formula 1 seat for the Italian.[56] A difficult opening Bahrain round saw Antonelli claim sole point from tenth place in the feature race, owing to a poor qualifying and the uncompetitiveness of his Prema.[57] He secured a pair of sixth place finishes in Jeddah from sixth, as Prema returned to form.[58] A sterling lap saw him second in qualifying at Melbourne,[59] but a spin whilst trying to make up ground saw him beach in the gravel during the sprint race.[60] In the feature race, he battled for the lead with Dennis Hauger, but was jumped by Isack Hadjar in the pit stops after the former crashed. Antonelli was later passed by two other drivers to end in fourth.[61]
He had a quiet weekend in Imola, but he finished in fourth again during the feature race as he fended off from Franco Colapinto.[62] In Monaco, Antonelli qualified seventh and finished fourth for the third time of asking in the sprint race.[63] In the feature race, Antonelli battled with teammate Bearman but was stuck behind Colapinto for almost the entire race, which caused him to finish in seventh.[64]