Pearl Jam's Mike McCready, Brad Paisley, and Smith's Red Hot Chili Peppers bandmate Josh Klinghoffer will also make up the nameless act, who will headline the Will Ferrell's Best Night of Your Life event at the Greek Theater in Los Angeles next month.
The gig will benefit Cancer for College, which offers scholarships to cancer survivors.
"I've had the opportunity to do a lot of amazing things in my life - for instance, there was that time I scaled Mount Everest with Barack Obama and members of the band Whitesnake," Ferrell jokes. "I once rode motorcycles through Ecuador with Mick Jagger and former Secretary of State Madeleine Albright..."
"So when I tell you that our big comedy and music extravaganza on October 6 at the Greek Theatre in Los Angeles is going to be the best night of your life, I'm speaking from experience..."
"Listen to me when I say you need to go right now to your local Ticketron, Tower Records, Licorice Pizza or wherever they sell concert tickets and get in line, because this show is going to be huge and it's going to sell out. I think that's all I need to say."