The Frenchman, who spent six years at Anfield, passed away just days after a heart operation.
The news was confirmed in France initially by both L'Equipe and RMC.
Houllier, who was awarded the Legion d'honneur for his services to French football, and an honorary OBE for services to British football, led Liverpool to an FA Cup, League Cup and UEFA Cup treble in 2001.
He spent 38 years as a manager, also taking charge of the France national team, Aston Villa, Lyon and Paris Saint-Germain, where he won Ligue 1 in 1986 - the first of PSG's nine titles.