He told BBC radio on Friday that he's been putting on weight and feeling better than he has in a decade.
The 62-year-old had suffered from severe weight loss in recent months and has been hospitalized for stomach and colon problems that forced him to cut back on public appearances.
He has not specified the exact nature of his condition but told the BBC he had a growth on his colon that had to be removed.
The singer says his doctors have been amazed by his recovery.
Gibb and his brothers scored many top hits during the disco era.
The Associated Press contributed to this report.