In June 2012, one week after his graduation from the UEFA Pro Licence, it was announced that Fournier would join FC Sion as manager in summer 2012. This marks the return to his childhood club and is linked with high expectations, even though it is his first station as a professional manager. He won the selection over Michel Decastel, because the club owner Christian Constantin wanted to have a young coach, after he was impressed with the achievements by Roberto Di Matteo, Pep Guardiola, André Villas-Boas and Murat Yakin. He was sacked as manager of Sion on 4 September 2012 due to a bad relationship between him and the squad.