[1] Mercadal began his managerial career as an assistant at his final playing club, Gap FC, before being their head coach between 2005 and 2008 in the fourth-tier Championnat de France Amateur.
For the next four years he was assistant at Amiens SC in Ligue 2 and the Championnat National;[2] he was interim manager on 23 October 2009 in a 1–0 loss at ES Troyes AC.
[6] Mercadal found another job in Ligue 2 in June 2017, being hired by Paris FC, who had been restored to the division after the administrative relegation of SC Bastia.
[8] On 8 June 2018, Mercadal was announced as the manager of Ligue 1 side Stade Malherbe Caen on a three-year deal, with Paris FC being compensated for the last year of his contract.
[11] He left by mutual consent on 25 May, after a 1–0 home loss to FC Girondins de Bordeaux on the final day and relegation to Ligue 2.