Fabio Di Giannantonio was born in Rome, and he first debuted in the Red Bull MotoGP Rookies Cup in 2014. In 2015, he finished as runner-up in the Red Bull MotoGP Rookies Cup and also in the CIV Moto3 championship. He also made his FIM Moto3 championship debut in 2015 with Gresini Racing Moto3 when he replaced injured rider Andrea Locatelli for the last race of the season. For 2016, he was signed full-time for the Gresini Moto3 team and he had a successful rookie season with a consistent streak of point finishes and three podiums. He remained with the team for the 2017 and 2018 seasons. 2017 was a solid season for the Italian with 5 podiums. 2018 was even stronger for Diggia as he achieved 6 podiums, two of which were grand prix wins, and went on to finish 2nd in the championship. In 2019, Diggia moved up to Moto2 with the Speed Up Racing Team. It was another consistent season for the Italian with point finishes and two podiums to finish in 9th overall. He remained with the team for 2020 but it was a tougher season for Diggia. Despite scoring two podiums, he failed to finish five race and was outside the points for four. For 2021, Diggia was back with Gresini this time in Moto2. He started the year strong with a third-place podium and achieved a further 3 podiums including a win to finish in 7th overall. 

2022 was the year that Fabio moved up to MotoGP, once again racing with the Gresini Team. It was a difficult rookie season as he only managed to finish in the points for 6 of the 20 races. Diggia remained with the Gresini Team for 2023 alongside Alex Marquez. Diggia took his first podium in Australia before taking his maiden win in Qatar. This late season form allowed Diggia to remain in MotoGP in 2024 with the VR46 team after Marc Marquez announced he'd be moving into Diggia's seat for 2024.