John Varty, 61, was attacked on his Tiger Canyons farm near Philippolis and taken to hospital for six hours of emergency surgery to treat multiple injuries and puncture wounds, Britain's The Guardian newspaper reported Thursday.
A spokeswoman for the Mediclinic hospital in Bloemfontein said Varty, who was taken in Wednesday evening, was conscious Thursday morning but not yet out of danger.
"He came in last night at around 9 o'clock and was treated in the trauma room," spokeswoman Amanda Appelgryn said.
"He went for 6-hour surgery and is in the intensive care unit. He had lost a lot of blood and got a transfusion in theater. He has multiple injuries on his front and back and all over his whole body but not his face.
"He's not stable and he's not critical but somewhere in between. It's best to say he's in a serious condition."
Controversy has swirled around Varty's farm, a project to create a free-ranging, self-sustaining tiger population. Critics have accused Varty of making money from the tigers by promoting the farm as a tourist attraction.
Varty has made more than 30 wildlife documentaries, including 1995's "Running Wild" in which he starred, about a conservationist trying to save leopards from extinction, with a cast that included Brooke Shields and Martin Sheen.