The Sin City actor was rushed to hospital last month after girlfriend Omarosa Maingault-Stallworth found him in a state of cardiac arrest.
While Duncan was immediately placed on a respirator due to trouble with his breathing, he has since improved enough to leave intensive care.
"His family are firm believers in the power of prayer and have asked that you keep him in yours during this time," Duncan's rep told People in a statement on Monday (August 6).
Maingault-Stallworth recently updated fans on Duncan's condition and expressed her hopes for his full recovery via Twitter.
"Everyday GOD continues to smile upon my luv Michael Clarke Duncan on this arduous road to recovery," she wrote, alongside a photo of herself with the Green Mile star.