The former U.S. track and field athlete and television personality revealed during an interview last night that he was transgender and identifies as a woman.
Jenner is the stepfather of reality TV stars the Kardashians who achieved fame on American series Keeping Up With The Kardashians.
"For all intents and purposes, I am a woman," he told ABC's Diane Sawyer.
The 65-year-old said he had always been confused about his gender identity.
"I am not gay," he said, "I am, as far as I know, heterosexual. I've always been with a woman, raising kids."
He said he was a devout Christian and didn't see any limitations on him practicing his faith as a transgender.
"When I would sit in church, I would always wonder. I had a revelation, maybe this is my cause in life. Maybe God put me on Earth to deal with this issue," he said, fighting back tears.
Asked whether he would undergo sexual reassignment surgery he replied: "These are all things that are out there in the future for me to explore.
"There's no rush for that. And I would do it so quietly that nobody in the world would know."
He added: "I have a feeling this is my cause in life. This is why God put me on this Earth, to deal with this issue."