Simone Barontini gained his first international experience in 2015 when he reached the finals at the European Youth Olympic Festival (EYOF) in Tbilisi , but could not finish his run there. In the following year he won the bronze medal at the European Youth Championships held there for the first time in 1: 49.78 minutes and in 2017 he reached the semi-finals at the U20 European Championships in Grosseto , in which he was eliminated with 1: 49.82 minutes. In 2018 he finished fifth at the U20 World Championships in Tampere in 1: 51.08 min and also qualified for the European Championships in Berlin , where he was eliminated in the first round with 1: 48.53 min. In the following year he failed at the European Indoor Championships in Glasgow with 1: 50.54 min also in the preliminary round and then reached eighth place at the U23 European Championships in Gävle in 1: 49.91 min.
In 2019 Barotini became Italian champion in the 800-meter run outdoors and from 2017 to 2020 also indoors.
Personal best
800 meters: 1: 46.87 min, August 27, 2019 in Rovereto
800 meters (hall): 1: 47.73 min, February 5, 2020 in Ostrava