Other ACM Awards performers include Jason Aldean, Toby Keith, Miranda Lambert, Brad Paisley, Taylor Swift and Keith Urban, Alabama, Dierks Bentley, Ronnie Dunn, Sara Evans, Martina McBride, Reba, Blake Shelton, Carrie Underwood and Zac Brown Band with James Taylor.
Robert Pattinson and his "Water for Elephants" co-star Reese Witherspoon have been tapped to present at the show, as have Seacrest and "Entertainment Tonight" correspondent Nancy O'Dell. Reba McEntire and Blake Shelton will host the ACM Awards, which will air on CBS.
The night will also be filled with A-list nominees including the contenders for Entertainer of the Year, Jason Aldean, Toby Keith, Miranda Lambert, Brad Paisley, Taylor Swift and Keith Urban. Swift is also up for Top Female Vocalist of the Year against Lambert, Reba McEntire, Carrie Underwood and Lee Ann Womack. Swift's Speak Now is also contending for Album of the Year.
In addition to her ACM performance, Rihanna is contributing music to a forthcoming digital-only album being compiled to benefit the victims of the Japan earthquake and tsunami. She also appears on the April cover of Vogue magazine.