Sebastiano Bianchetti gained his first international experience in 2013 at the Youth World Championships in Donetsk , where he failed to make a valid attempt in the final, as well as at the Junior World Championships the following year in Eugene , where he did not succeed in qualifying. In 2015 he won the bronze medal at the European Junior Championships in Eskilstuna with a width of 20.71 m with the 6 kg ball and was eliminated in the discus throw with 54.23 m in qualification. The following year he won the silver medal behind Egyptian Mohamed Magdi Hamza at the U23 Mediterranean Championships in Tunis with 18.77 m and also qualified for the European Championships in Amsterdam , where he did not reach the final with 18.56 m . In 2017 he won the bronze medal at the U23 European Championships in Bydgoszcz with 19.69 m and in 2018 he again won the silver medal at the U23 Mediterranean Championships in Jesolo with 19.31 m, this time behind compatriot Leonardo Fabbri . He then took part in the Mediterranean Games in Tarragona and was fourth there with a push of 19.71 m. In 2019 he finished fifth at the Summer Universiade in Naples with 19.81 m.
From 2016 to 2018 Bianchetti was the Italian champion in the shot put outdoors and in 2017 also indoors.