"It was proposed to me as a legitimate interview to speak about veterans’ issues in our military and current events to a new audience," she said in an exclusive interview with "Good Morning America." "It was supposed to be this big time Showtime documentary and it was passed on to me by a speakers’ bureau, which, you know, I would assume had done some vetting."
The former Alaska governor said in a Facebook post earlier this week that she traveled "across the country" for an interview with Baron Cohen, whom she claims "heavily disguised himself as a disabled U.S. veteran, fake wheelchair and all.”
She slammed the act as "evil" and "sick," and added that she "literally, physically removed" her mic and walked out of the interview.
"He started showing me these graphs and statistics that had like typos in them and just didn’t quite look right and part of this propaganda, this data that he was showing me, had something to do with sex changes and transgenderism and he brought up Chelsea Clinton and said she was a recipient of a government-funded sex change," Palin said on "GMA." "It just got worse and worse and worse as the minutes went on in this bizarre, really embarrassing, humiliating interview."
She continued, "It was occurring to me, whatever this show is, whatever this interview really is, is all about humiliation and devaluing middle-class Americans, whom I represent. I said, ‘Enough was enough,’ and I took off my mic and I walked out."
Baron Cohen has made a career out of conducting prank interviews with unwitting celebrities, including Donald Trump before he became president.
The comedian filmed the latest stunt for his forthcoming Showtime series, "Who Is America?" -- which is expected to feature a spectrum of new, high-profile gags.
Baron Cohen teased the "Who Is America?" series in a Twitter post Sunday, where an off-screen voice with an odd accent can be heard asking former Vice President Dick Cheney to "sign my waterboard kit."
Cheney, who as vice president was a hawkish defender of harsh interrogation techniques, goes along with the request, autographing a gallon-sized plastic jug.
Palin has challenged Baron Cohen to donate all proceeds from "Who Is America?" to a charity that "actually respects and supports American Vets."
She said Friday that she has yet to hear from the show's producers.
"Since [the interview], nobody returns my calls," she said. "They had given us fake names as to producers and anybody involved in the show. Nobody has taken me up on my offer for them to donate the proceeds from the show to veterans’ organizations that truly support and respect our vets."
Billy Wayne Ruddick, Jr, PhD, Baron Cohen's character from "Who Is America?," posted a rebuttal to Palin on Thursday, claiming he did not pose as a military veteran.
Baron Cohen later retweeted it from his own account.
Showtime declined to provide a clip of Baron Cohen's interview with Palin to ABC News.
"You read a line like that and, you know, man, this guy, he just doesn’t quit," Palin said, referring to the line about bone spurs in Baron Cohen's character's rebuttal. "He thinks this kind of stuff is funny, and mocking the disabled and mocking and belittling our vets with his portrayal, in my book, it’s not funny."
She added, "This actor, this comedian, whomever he is, he’s a proven liar. Nobody can believe a word he’s saying now as to his rebuttal."
Showtime declined ABC News' request for comment, and Baron Cohen did not respond to requests for comment Thursday evening.
Palin said she is speaking out about her experience now because she feels it is "important" to "let people know what's coming."
"If people tune into this show, then they’re going to see how middle-class Americans are mocked and our values are mocked," she said. "If people do decide to tune in, they’re going to hear about it anyway, if they tune in, well the ill-gotten gains by CBS and Showtime, those, I say, need to be donated to people who deserve the gains."
ABC News' Lee Harris contributed to this report