The site also confirmed that Amazon Studios has bought rights to the project, which will be produced by the Hollywood couple’s children, Lucie Arnaz and Desi Arnaz Jr., along with Todd Black, Jason Blumenthal and Steve Tisch from Escape Artists.
ET confirmed Blanchett, 48, was attached to the biopic in September, 2015. At the time, Sorkin -- who created The Newsroom and The West Wing -- faced backlash on social media about his involvement as the screenwriter.
While there’s no word on when filming might commence, Blanchett is meanwhile busy promoting another epic role -- that of Hela, in the Taika Waititi-helmed Thor: Ragnorak, which hits theaters on Nov. 17.
"I only realized that when I got on set and you think, 'Wow! It's taken this long to catch up!'" she told ET about playing being the first real female villain in the Marvel universe. “Marvel is catching up at a rapid, rapid rate. You've got Captain Marvel coming out with Brie [Larson] and all these incredible women who are in Black Panther ... and Scarlett [Johansson] of course."
"It was her first experience of being on set with me, so she thinks that's what I do all the time," she shared. "She thinks acting is manifesting weapons out of your hands and killing people."
See more from ET’s chat with the Australian beauty below.