The 30-year-old was reportedly found on the ground by a passer-by in a forest area on the outskirts of Paris after taking a cocktail of drugs and alcohol on Sunday.
According to Sky News, Lenoir's boyfriend, football player Claude Makélélé, initially called emergency services after finding her slumped on the floor of his Paris home. However, she apparently woke up and called to cancel the ambulance, only to leave the house to be found unconscious hours later.
The French-born model was also the face of campaigns for Next, Gap and Victoria's Secret.
She is currently recovering in hospital.