Johan Gastien

Gastien started his career with his home-town club Niort and made his debut in the 2–1 victory over Libourne-Saint-Seurin in Ligue 2 on 28 March 2008, coming on as a substitute for Ronan Biger. On 27 March 2010, he scored his first senior goal in Niort's 1–0 victory over Toulouse Fontaines, but was sent off later in the match. Gastien was part of the team that won promotion from the Championnat de France amateur in 2010 and subsequently promotion back to Ligue 2 two years later. In total, he played 140 league matches during six senior seasons with the club, scoring 14 goals. On 25 May 2013, it was announced that Gastien had agreed a contract with Dijon for the 2013–14 season.

As of match played 19 May 2024

He is the son of football manager and former player, Pascal Gastien. Johan has been coached by his father at Niort and Clermont.