Winfrey will make a rare late-night appearance at a time when her cable channel, OWN, is trying to attract viewers after a rocky start in its first year.
Oscar host Billy Crystal will help kick off "Jimmy Kimmel Live: After the Academy Awards," and nominees Meryl Streep, George Clooney and Martin Scorsese will also be among the stars on hand.
Also, Coldplay will perform to wrap up the show.
Leading up to the ceremony, "On The Red Carpet" co-host Rachel Smith will be doing interviews with hair and fashion stylists and makeup artists for the "Best Dressed" video series featured on Oscar.com, beginning on Feb. 11. Smith will also be covering live events and offering post-show analysis of Oscar night fashions for the site.
It was announced in November, that Billy Crystal would return to host the 84th annual Academy Awards.
The awards ceremony will air live on Sunday, Feb. 26, 2012 on ABC7. Coverage begins at noon PT.
OnTheRedCarpet.com will have complete coverage of the Oscar season, including an exclusive interactive live stream show LIVE from the red carpet. Follow @OnTheRedCarpet on Twitter and "Like" On The Red Carpet on Facebook, and download our FREE entertainment news app for the iPhone and iPad.
KABC-TV LOS ANGELES, CA contributed to this report.