"James is a truly talented singer-songwriter," John said in a statement. "His voice and expressive lyrics enchant audiences worldwide. I have no doubt that he will do the same for our guests on Oscar night."
Blunt, 32, is up for five awards at the Grammys, which will air live on CBS on Sunday. His double-platinum debut album, "Back to Bedlam," yielded the smash hit "You're Beautiful." He toured with John in 2004, reports AP.
The Elton John AIDS Foundation has raised nearly $120 million (EUR92 million) to support HIV/AIDS prevention and services since it was founded in 1992.