The 43-year-old admitted he’d “done a Rooney” during a grilling by Piers Morgan for his upcoming show, Life Stories.
The Australian singer and former Neighbours star said: “I did have a small procedure four years ago and am really happy with the results.
“It’s something I did for just for myself and haven’t ever felt the need to publicise it.”
Donovan has always refused to divulge his treatment, even though it looked thicker on Strictly.
A friend said: “This is not just Jason being vain. He is a guy who works in showbusiness and he feels more comfortable with hair.”
He confessed after Morgan made a joke about him having thicker hair, said the source.
Wayne Rooney spoke out last year about his wish for more hair, after he had undergone a follicular transfer, which moves hairs from areas where they grow thickly to the bald areas.
He said: “Just to confirm to all my followers I have had a hair transplant. I was going bald at 25, why not? I’m delighted with the result.”
Donovan will headline a concert in Hyde Park this summer with his old flame, Kylie Minogue, 43 who he dated during their time as an on-screen couple in Neighbours.