Caitlyn Jenner, the transgender Olympic champion formerly known as Bruce, on Monday unveiled her new name and look in a sexy Vanity Fair cover shoot - drawing widespread praise, including from the White House.
Lesbian, gay, bisexual and transgender campaigners - and many well-wishers - welcomed the high-profile debut, as did the 65-year-old Jenner's family, which includes the media-savvy celebrity Kardashian clan.
"I'm so happy after such a long struggle to be living my true self," Jenner wrote in her first tweet after the magazine released the July cover photo by renowned photographer Annie Leibovitz.
"Welcome to the world Caitlyn. Can't wait for you to get to know her/me," added Jenner, who sported a cream-colored strapless bodysuit and long brown hair for Vanity Fair's July issue.
In a video clip of the photo shoot on the magazine's website, Jenner said: "Bruce always had to tell a lie. He was always living that lie. Every day, he always had a secret, from morning till night.
"Caitlyn doesn't have any secrets," said Jenner, a reality television star, who is also shown in a black evening gown in the video.
"As soon as the Vanity Fair cover comes out, I am free," she said.
"Caitlyn Jenner" and the hashtag #CallMeCaitlyn quickly rocketed to the top of the Twitterverse as the top trending topic in the US and worldwide.
Jenner's Twitter feed scooped up nearly 900,000 followers within about three hours of her first tweet.
Jenner was widely praised for revealing in a television interview broadcast in April that she was transitioning to life as a woman, earning praise for coming out as transgender.
LGBT groups hailed Jenner's Vanity Fair cover story.
"By sharing her journey with the world, Caitlyn Jenner is accelerating acceptance of transgender people everywhere and reminds us all how important it is to live as your most authentic self," GLAAD head Sarah Kate Ellis said.
"For a transgender person to step into the world as his or her authentic self is a moment of tremendous freedom," said Nick Adams, GLAAD's Director of Programs, Transgender Media.
"The world can now see what Caitlyn Jenner has always known, that she is - and always has been - a woman."
Jenner's family also quickly rallied around her on Twitter.
"How beautiful! Be happy, be proud, live life YOUR way!" wrote Kim Kardashian, Jenner's step-daughter and fellow reality television star.
The outpouring of support on Twitter also included a message from Valerie Jarrett, senior advisor to President Barack Obama and chairwoman of the White House Council on Women and Girls.
"Nice to meet you,
"Be free now pretty bird."
Khloe Kardashian, another of Jenner's step-daughters, wrote on Instagram: "We were given this life because you were strong enough to live it! I couldn't be prouder!!!
"Caitlyn, You are beautiful!!!"
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