Stefano Viezzi (born 5 February 2006) is an Italian cyclist, who rides for UCI Continental team . In 2024, he became the Junior Cyclo-Cross World Champion.
He started bike racing at seven years-old. He studies agriculture at the Istituto d'Istruzione Superiore Il Tagliamento in Spilimbergo.
A keen road racer, cyclocross rider and also mountain biking rider, he has described his road racing skills as best suited to one-day classics riding. He raced for in 2023 and finished in the top 10 at the Italian junior time trial championship. He won seven of the first eight cyclo cross races he took part in 2023, and finished fourth in the junior event at the UEC European Cyclo-cross Championships in Pontchâteau.
He won the Junior race at the 2024 UCI Cyclo-cross World Championships in Tábor. The win came despite the fact he suffered a puncture in the closing stages. He became the first Italian winner in the race since Davide Malacarne in 2005. Prior to that win, he had also become the Italian junior champion.
From Majano, his parents are called Luigi and Michela. His father runs a marble company. He has two sisters, Elisa and Alice.