The roundtable has generally had five hosts, including Walters, throughout its history. This season there are four.
O'Donnell, the veteran comedian whose daytime talk show was wildly popular in the 1990s, spent a combative eight months on "The View," ending in 2007. She frequently made news, feuding with the likes of Donald Trump and Rupert Murdoch, and the show's ratings went up. But after a nasty on-air argument with co-host Elisabeth Hasselbeck, O'Donnell asked to be let out of her contract.
Hasselbeck is gone now, having left "The View" to join Fox News Channel.
O'Donnell briefly hosted a talk show on Oprah Winfrey's OWN network, but it drew little interest. She came back as a guest on "The View" in February, a sign that relations had thawed.
ABC would not comment Thursday on O'Donnell's return, other than its tweet. O'Donnell's spokeswoman, Cindi Berger, didn't immediately return messages for comment.
O'Donnell was moderator of "The View" during her eight months, which meant she generally guided conversations on the show. Goldberg has assumed that role, and is expected to keep it.
ABC hasn't commented on who is under consideration to join Goldberg and O'Donnell. Guest hosts, however, are often a signal of people trying out for the job. Meghan McCain, daughter of Arizona Sen. John McCain who has her own show on the Pivot network, will be a guest host next week. Abby Huntsman, daughter of former Republican presidential candidate Jon Huntsman, has been a guest in the past. Lawyer Sunny Hostin is scheduled for a future guest host role.
Former Alaska Gov. and Fox News personality Sarah Palin has expressed interest in a job at "The View," but there is no indication that she is under consideration by ABC.
McCarthy and Shepherd will remain with the show until the week of Aug. 11, when it goes on summer hiatus. O'Donnell will join with the start of a new season on Sept. 15.