Los Angeles - Bruce Jenner is set to do a tell-all interview about his transition from male to female.
The Keeping Up with the Kardashians star is to open up to ABC News journalist Diane Sawyer about his life change in a one-off special which is expected to be aired in May.
A source revealed the 65-year-old former athlete opted for the established broadcaster because she has long been a supporter of transgender rights.
The insider said: "Diane has always been very supportive of the LGBT community."
Work on the "major sit down interview" is set to commence this week, with progress on creating an unscripted E! series following his transition - tentatively titled Bruce Jenner - My Story - already underway.
Speaking about the series, a source told Us Weekly: "The world will see his full transformation.
"It's a docuseries featuring the Jenner family talking about Bruce 'coming out'."
Last week, the publication reported his decision to air an exclusive interview with ABC as well as a docuseries of his own is causing "internal consternation" in NBC's news division, which is owned by the same company as E!, as they were hoping they would be able to secure the chat.
Bruce's step-daughter Kim Kardashian West recently spoke out in support of his life decision, describing his change as part of a "journey".
She said: "I think everyone goes through things in life, and I think that story and what Bruce is going through, I think he'll share whenever the time is right. I feel like that's his journey to talk about."
Diane, 69, stepped down as ABC's World News anchor last year to focus on one-off specials and high-profile interviews.