Born in Sevrier, Haute-Savoie, he was first elected to his hometown's council in 1977.[2] He became deputy mayor in 1989, serving behind Pierre Hérisson. In 2008, when Hérisson ended his 31-year tenure to run for mayor of the departmental seat Annecy, Rey was elected mayor ahead of Hérisson's preferred candidate Isabelle Payen.[3] He was also a delegate to the Communauté d'agglomération du Grand Annecy in the area of water management.[4]
In 2019, Rey announced that he would not run for reelection the following year.[2] He was succeeded in May by his former assistant for town planning, Bruno Lyonnaz.[5] In January 2022, the 79-year-old entered national politics for the first time when he succeeded Frédérique Lardet as deputy in the National Assembly for Haute-Savoie's 2nd constituency; she had left to become president of Grand Annecy.[6] In June's elections, he did not stand, with LREM instead represented by Antoine Armand.[7]