The actor, who portrayed inept magician Gob Bluth on the short-lived Fox sitcom, told Coming Soon that he expects the big screen spinoff to go into production this year.
"We are working on the movie right now," he said. "We don't have a completed script yet, but it's forthcoming and we're going to make the movie this year."
Arnett joked that the cast and filmmakers are waiting for series star Jason Bateman to "get out of rehab" before filming commences.
Arrested Development creator Mitchell Hurwitz will direct the movie with stars Bateman, Arnett, Michael Cera, Jeffrey Tambor, Jessica Walter, David Cross, Portia de Rossi, Alia Shawkat and Tony Hale all expected to reprise their roles for the feature.