Smith will next star in the movie "Focus."
U2, which hasn't had an album since 2009's "No Line on the Horizon," is to release a new album this year.
The 22-time Grammy Award-winning band was nominated last week for an Academy Award for Best Original Song for "Ordinary Love" from the film, "Mandela: Long Walk to Freedom."
Fallon is taking over the "Tonight" host's chair from Jay Leno, who started on the show in 1992.
2014: The Year in Music [PHOTOS]