Stefano Manzi started his racing career in 2007, the Italian achieving fifth place in the Italian Minimoto Championship Junior A contest, then in 2009 he took the HIRP Championship riding a Honda 50cc – followed by winning the 2010 Italian MiniGP Championship on a Metrakit 50 with seven race victories. In 2011 Manzi won the 70cc category in the same championship. In 2012 he finished thirteenth in the Red Bull Rookies Cup overall, then third the following year and in 2014. For 2015 he joined the Moto3™ team ‘San Carlo Team Italia’, riding a Mahindra alongside Matteo Ferrari. He earned 10 points throughout the year and stayed with the team again in 2016, with some notable performances including battling in the front group at Silverstone, alongside racing in the FIM CEV Repsol Junior Moto3™ World Championship. Manzi, who is over six feet tall, moved up to Moto2™ with the new Sky Racing Team VR46 intermediate class project for 2017. After a tough start he found some traction towards the end of the season, and moved to Forward Racing Team on board a Suter for 2018 to continue his progress. After a difficult season for Manzi, which saw him miss the final three rounds of the season, he remained with Forward Racing for 2019 as he and the team got to grips with an MV Agusta chassis, while the Italian factory made their Grand Prix racing return. Manzi finished the campaign with the best result of his career, taking 4th in Valencia. However, 2020 was, again, a difficult year for him, where his best result was a ninth position in the Andalusian GP. In 2021, he makes the move to Pons HP 40.