Officials said a Chinese national had imported the animal and was raising it at a villa in the capital Phnom Penh.
They launched their investigation in April, after discovering footage of the 70kg (11st) lion on TikTok.
The 18-month-old animal was moved to a wildlife rescue centre.
Authorities have not announced whether the owner will face any legal action.
Environment ministry spokesman Neth Pheaktra told AFP news agency that images shared on TikTok showed the lion sitting on a driveway and being sprayed down with a hose as a young cub.