The 52-year-old actress/comedian was considered to take the hosting gig because she has what it takes to add some controversy and drive the ratings up, reported Ace Showbiz qouting Fox 411.
"The network executives really wanted Rosie back," a source said.
O'Donnell previously served as a co-host on the show between September 2006 and May 2007 but she did return as a guest on the show in February.
A few days ago, Sherri Shepherd announced her exit from the show after seven years.
Co-host McCarthy then hinted on Twitter that she would leave too, leaving Whoopi Goldberg as the sole host following Barbara Walters' recent retirement.
The network said there are lot of speculation about possible replacements but they were not ready to make any announcements as yet.