Le Mignan spent his entire playing career in the French lower leagues with Montagnarde, Pontivy, Locminé and Vannes. He took up coaching following his retirement in 2001 and the following year, aged 28, he was appointed manager of Vannes following the departure of Denis Goavec. In 2005, Le Mignan led the team to the Championnat de France amateur Group D title and subsequent promotion to the Championnat National. Three years later, Vannes were crowned champions of the National as they finished four points ahead of Tours. Le Mignan guided the team to safety in their first season in the professional Ligue 2 in 2008–09. Vannes remained in the second tier of French football until 2011, when they were relegated back to the National. On 27 December 2012, he left Vannes where he spent almost 10 years as manager.