*Club domestic league appearances and goals, correct as of 18:37, 01 December 2024 (UTC). ‡ National team caps and goals, correct as of 18 November 2024
Sierro was born in Sion, in the canton of Valais in the southwest of Switzerland. He is the son of former Valais State Councillor Serge Sierro.[3]
His father having played for Sierre and the Valais regional squad, and his grandfather amongst the founders of FC Crans-Montana, Sierro grew up in a footballing family.[3] Sierro joined the academy of FC Sion, in his hometown, in his youth.
Club career
Sierro began his senior career in the Swiss third division with the FC Sion B team during the 2013-2014 season. He made his debut with the FC Sion first team during the 2014-15 season. He scored his first goal on the 10 April 2016 against FC Thun.[4]
In January 2017, Sierro signed for SC Freiburg on a four-year contract. He did not find success at the club, and returned to Switzerland for the 2018–19 season, joining St. Gallen on loan.[5]
In June 2019, Sierro signed a four-year contract with Young Boys.[6]
In January 2023, Sierro signed for Ligue 1 club Toulouse.[7] Sierro was named club captain ahead of the 2023-24 season.[8]
Sierro was included in Switzerland's preliminary squad ahead of the UEFA Euro 2024 on 17 May.[12] He was named in the final 26-man squad on 7 June.[13] In said tournament on 15 June, Sierro appeared as an 86th-minute substitute for Remo Freuler in Switzerland's opening Group A fixture against Hungary.[14]
Career statistics
Club
As of match played 12 May 2024
Appearances and goals by club, season and competition