Peters will play Ivy, the Tony Award-winning mother of Megan Hilty's character, Leigh, who lives vicariously through her daughter.
Jonas will play Lyle West, a hot sitcom star who started his career as a child actor in a Broadway show written and directed by two of the series regulars: Tom (Christian Borle) and Derek (Jack Davenport), respectively.
Peters is currently starring in the Broadway revival of Follies. She has won two Tony Awards: for her performances in Song and Dance and Annie Get Your Gun. Among her numerous other Broadway credits are the original productions of Sunday in the Park With George and Into the Woods, and revivals of Gypsy and A Little Night Music.
Jonas, who as previously reported, will join the Broadway production of How to Succeed in Business Without Really Trying on January 24, is a member of the popular music group, The Jonas Brothers. He appeared on Broadway in Les Miserables, Annie Get Your Gun, and Beauty and the Beast, and his other stage credits include A Christmas Carol and the Hollywood Bowl's recent production of Hairspray.
Smash, which will have original songs by Tony Award winners Marc Shaiman and Scott Wittman, chronicles the mounting of a Broadway show. The cast also features Will Chase, Anjelica Huston, Brian d'Arcy James, Debra Messing, and Katharine McPhee.