Kim Kardashian's stepfather Bruce Jenner has made his debut as a transgender woman called Caitlyn in the latest issue of Vanity Fair.

"Call me Caitlyn," declares a headline on the cover, with a photo of a long-haired Jenner in a strapless corset, legs crossed, sitting on a stool.

The image was shot by famed celeb photographer Annie Leibovitz. Inside, more images show Jenner in gold lame, a black bustier and a cleavage-baring, off-the-shoulder gown.

Jenner also debuted new Twitter account @Caitlyn_Jenner with: "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."

The account broke a record for fastest time to reach one million followers, besting President Barack Obama's new @Potus handle with a mark of 4 hours and 3 minutes, according to Guinness World Records.

Vanity Fair took to Twitter with the cover and said Jenner spoke emotionally about her gender journey: "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.'"

The cover comes after a two-hour ABC interview with Diane Sawyer in which Jenner confirmed the transition. The much-anticipated 20/20 interview on April 24 was watched by more than 17.1 million viewers.

Prior to the unveiling of Caitlyn, Jenner had said he preferred the pronoun "he", but Vanity Fair contributing editor Buzz Bissinger, who wrote the story, refers to "she".

The Olympian who married and divorced reality show "momager" Kris Jenner has appeared for years on Keeping Up with the Kardashians. Jenner's own still-untitled docu-series chronicling her transition is scheduled for the same US TV network, E!, beginning July 26.

Vanity Fair also released a black-and-white video on the making of the cover.

"Caitlyn doesn't have any secrets," Jenner narrates. "As soon as the Vanity Fair cover comes out, I'm free."

Bissinger, the Friday Night Lights Pulitzer Prize winner, said in the lengthy magazine story that he had unfettered access to Jenner, both before her transition and after.

His approach to Jenner's life is exhaustive, based on interviews with several of her biological children, her mother, her former wives and others.

The story describes Jenner's painful recovery from "facial-feminisation" surgery in March, a gruelling 10-hour procedure that had Jenner briefly second-guessing the decision during a panic attack eased in part with the help of a Los Angeles Gender Center counselor who made a house call. There was also a breast-augmentation procedure.

Now, Bissinger reports, the 65-year-old Jenner is "immensely happy, relaxed, with a shiny sense of purpose and confidence". He added: "She can't wait when she goes out now to tell the paparazzi to 'make sure it's a good shot'."

Of the upcoming reality series, Jenner is already prepared with a response over criticism that she's doing it for a pay cheque.

"I'm not doing it for money. I'm doing it to help my soul and help other people. If I can make a dollar, I certainly am not stupid. (I have) house payments and all that kind of stuff. I will never make an excuse for something like that. Yeah, this is a business."

Jenner said she is aware of the appalling conditions in which many of the 700,000 transgender men and women live in the US and plans to shed light in the E! show on such issues as suicide and attempted suicide within the community.

She also plans a segment in which she sees if she can still hit a golf ball 300 yards off the tee with her new physical attributes.

A road trip is planned on the new show for Jenner and several transgender women to travel from Los Angeles to San Francisco to visit a centre for transgender youth.

On July 15, is Jenner planning her first major public appearance. She will be given the Arthur Ashe Courage Award at ESPN's ESPYs in Los Angeles.

Past winners include Muhammad Ali, Nelson Mandela and Billie Jean King.

Among big names to reach out on Twitter in support of Jenner's reveal were some of his children, LGBT advocates and Valerie Jarrett, senior adviser to President Barack Obama.

"Nice to meet you, @Caitlyn_Jenner," Ms Jarrett tweeted (and was retweeted by the White House). "The brave choice to live as your authentic self is a powerful example to so many."

Jenner's loved ones were among numerous well-wishers to support her coming out.

Her stepdaughter, Kim Kardashian West, tweeted: "How beautiful! Be happy, be proud, live life YOUR way!"

Khloe Kardashian declared: "We were given this life because you were strong enough to live it! I couldn't be prouder!!! Caitlyn ." The third Kardashian sister, Kourtney, chimed in: "Freedom! Stunning."

Jenner daughter Kendall Jenner added "be free now pretty bird". Her little sister Kylie Jenner took to Instagram with the cover and this sentiment: "My angel on earth!"

Among others to welcome Caitlyn was Lady Gaga, who tweeted: "thanku for being a part of all of our lives & using your platform to change people's minds."

The lesbian, gay, bisexual and transgender advocacy organisation GLAAD promptly issued tips and terminology for referring to transgender people.

"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," said Sarah Kate Ellis, GLAAD's president and CEO.

From the fashion world, designer Zac Posen offered: "Be who you are and feel beautiful."

And Jesse Tyler Ferguson, from sitcom Modern Family, made reference to another famous magazine cover, that of Paper, Kim Kardashian and her famous arc of Champagne from bottle to derriere: "CaitlynJenner has truly broken the Internet. What a moment.'"