Born in Caen, Calvados,[3] Costil started his career at Caen in Ligue 1 but only made a 10 performances for the club before being sent on loan in the 2008–09 season to Vannes in Ligue 2.[citation needed]
On 17 June 2009, Sedan signed Costil from Caen until June 2011.[5] In two years at Sedan he made 76 appearances and was elected best goalkeeper of Ligue 2 for the 2010–11 season.[citation needed]
Rennes
On 14 June 2011, he signed a three-year contract for Rennes after his contract with Sedan expired. This transfer meant he returned to Ligue 1 for the first time since the handful of appearances he made at Caen at the beginning of his career.[citation needed]
Bordeaux
In 2017, Costil joined Bordeaux. In July 2019, he extended contract until 2022 and was named the team captain. However, following the signing of Laurent Koscielny, he was relegated to vice-captain. [citation needed] In 2022, Costil confirmed his departure from Bordeaux.[6]
Auxerre
On 16 July 2022, newly promoted Ligue 1 team Auxerre announced the signing of Costil for free, on a one-year deal.[7]
He made his debut on 15 November against Ivory Coast, playing the whole game, also captaining his side in a 0–0 home draw. He kept the first clean sheet.[10]
In September 2018, after Steve Mandanda got injured, Deschamps called Costil up to the national team for matches against Germany and the Netherlands in the UEFA Nations League.[12]
^"Costil Events". Verif (in French). NextInteractive. Retrieved 8 March 2020. "Benoit Costil". BFM Business (in French). NextInteractive. Retrieved 8 March 2020.