MTV announced on Aug. 22 that Maroulis would join the show on Sept. 8. No specific role was mentioned.
A production spokesperson said Maroulis is in negotiations.
The New York native was among the top 12 "Idol" contestants in 2005. He was voted off the show on April 27, 2005.
The Wedding Singer stars Stephen Lynch as Robbie Hart and also features Richard Blake, Kevin Cahoon, Felicia Finley, Rita Gardner, Matthew Saldivar and Amy Spanger.
The score was composed by Matthew Sklar (music) and Chad Beguelin (lyrics). Beguelin and Tim Herlihy wrote the book for the musical. The show's original cast recording hit stores June 6 on the Masterworks Broadway label. In The Wedding Singer "it's 1985 and rock-star wannabe Robbie Hart is New Jersey's favorite wedding singer," according to the producers. "He's the life of the party-until his own fiancée leaves him at the altar. Shot through the heart, Robbie makes every wedding he plays as disastrous as his own. Enter Julia, a winsome waitress who wins his affection. Only trouble is Julia is about to be married to a Wall Street shark, and unless Robbie can pull off the performance of the decade, the girl of his dreams will be gone forever. With a brand new score that pays loving homage to the pop songs of the 1980s, The Wedding Singer takes us back to a time when hair was big, greed was good, collars were up, and a wedding singer just might be the coolest guy in the room."
Laura Benanti, the co-star of Broadway's The Wedding Singer, recently began a lengthy medical leave from the new musical.
"As you may be aware," Benanti wrote on her official website on Aug. 10, "I am on medical leave from The Wedding Singer for the next four to six weeks. I want to thank the cast of The Wedding Singer (especially Tina Maddigan) and everyone who has been so kind to me and supportive during this difficult time, and I want you all to know I am doing everything I can to get healthy and get back to the show to stay!"
Tina Maddigan will play the role of waitress Julia Sullivan in Benanti's absence.