Farrow, 28, posted a letter on the New York Times website last weekend, disclosing harrowing details about what she claims was her adopted father's repeated sexual abuse of her as a child.
While Farrow's brother Ronan and mother Mia have publicly supported Farrow's decision to tell her story, another brother Moses said he believes the allegations are the result of Mia turning her children against Allen because he left her for her adopted 19-year-old daughter, Soon-Yi Previn in 1992. Allen has always emphatically denied Farrow's claims.
O'Donnell, who revealed years ago she herself is a sex abuse survivor, said she is a close friend of Mia's and "totally believes" her daughter's allegations.
O'Donnell further noted a decision was made more than 20 years ago not to charge Allen with any crime because a trial would be traumatic for Farrow, who was then 7.
While Walters again defended Allen as a good father, O'Donnell reminded her, "You can never really know what's going on in a house."
"We'll move on," Walters said, changing the subject.
Friday's visit to "The View" was O'Donnell's first since she left the show in 2007 after a series of disputes with her conservative co-host Elisabeth Hasselbeck, who has since left the program for a job at Fox News.