Bruce Jenner allegedly underwent full gender reassignment surgery, and is now officially a woman.
The 65-year-old former Olympic star had recently revealed that he is turning into a woman, during an interview with Diane Sawyer.
According to a report in Radar Online, the Keeping Up With The Kardashians star, who was married three times and has fathered six children, underwent the surgery "over three weeks ago".
"The procedure involved reshaping Bruce's male genitalia into that of a woman. He was very happy with the results, but didn't realise how grueling the recovery would be," a source told the website.
"The surgery was more than eight hours long," the insider added. "In the immediate aftermath, Bruce thought he had a urinary tract infection, but it was simply the pain from the procedure."
"Bruce is officially, and for all legal purposes, considered a woman," the source continued. "Bruce's kids have never seen him so happy. They just wish he would publicly start living as a woman, but contractually, he has to keep it under wraps until the docu-series premieres."
Last year, Kris Jenner's husband checked into the Beverly Hills Surgical Center for a laryngeal shave – a surgery to reduce the appearance of the Adam's apple – sparking rumours that the reality TV star was transitioning from male to female.
He also allegedly started taking oestrogen and asked to be referred to as "Brigitte".
In February, Bruce's mother, Esther Jenner, confirmed that her son is transitioning into a woman.