The first photo of Caitlyn Jenner, formerly Bruce, has been made public.
The Kardashian star appears on the cover of the latest issue of Vanity Fair.
Jenner revealed last month he was planning to live life as a woman.
And now she has told Vanity Fair: "If I was lying on my deathbed and I had kept this secret and never ever did anything about it, I would be lying there saying, 'You just blew your entire life'."
After the cover was revealed, Jenner opened a new Twitter account with the biography: "I'm so happy after such a long struggle to be living my true self.
"Welcome to the world Caitlyn. Can't wait for you to get to know her/me."
Jenner's transition was revealed in a two-hour programme on ABC that was watched by 16.9 million viewers.
He told Diane Sawyer that "to all intents and purposes I am a woman" and said he had felt that way since childhood.
"I've always been confused about my gender identity.
"I'm not stuck in anybody's body. My brain is much more female than male. People look at me differently. They see you as this macho male, but my heart and my soul and everything that I do in life, it is part of me, that female side is part of me."
In 1976 Jenner won a gold medal in the Olympic decathlon before gaining commercial success in advertising and television.
For the past decade he has been better known as the stepfather in the hit reality TV series Keeping Up With The Kardashians.
Jenner has been married three times and has six children.
He told Sawyer that Kim Kardashian had handled the news of his transition best, while Khloe had struggled to come to terms with it.
The sisters tweeted that they had watched the interview.
Kim Kardashian wrote: "Love is the courage to live the truest, best version of yourself. Bruce is love. I love you Bruce. #ProudDaughter."
She later added: "Your honesty has opened the doors for others to be courageous and live an authentic life!"
Khloe Kardashian tweeted: "Just finished watching the #BruceJennerInterview with the family. Bruzer, I'm soooo proud of you! Dads really are heros."