Parton, will sing along with the cast of "9 to 5: The Musical"; John with the cast of "Billy Elliot: The Musical," and Minnelli, Channing and Poison along with the cast of "Rock of Ages."
This year's Tony Awards will honor the best in Broadway theater for the 2008-09 season.
Neil Patrick Harris, star of the CBS comedy "How I Met Your Mother," has been named host of the awards show, which will be broadcast for the first time in high-definition.
NBC reportedly holds celebs hostage to Jimmy Fallon's show
Aaron Carter is still in love with Hilary Duff