The 2011 Ligue 1 champions have decided to part company with the experienced goalkeeper, but are yet to reveal the reasons behind his departure
A number of reports on Thursday suggested that the 33-year-old was on his way out of the club, and LOSC have now confirmed Landreau's departure.
"LOSC and Mickael Landreau have decided by mutual consent to end their collaboration. The club and the goalkeeper have today [Friday] signed an agreement to end his contract with immediate effect," an official statement reads.
No details have been disclosed for the experienced goalkeeper's exit by either of the two parties involved.
Landreau started his professional career at Nantes and also wore the jersey of Paris Saint-Germain before joining Lille in the summer of 2009.
He has since made over 100 official appearances for the Dogues, winning a Coupe de France and Ligue 1 title in the process.