Thesp Jeffrey Tambor (“The Larry Sanders Show”) has officially joined the cast of Fox’s upcoming laffer “Arrested Development.”

Tambor had previously been slated only as a guest star on the 20th Century Fox TV/Imagine TV comedy, which stars Jason Bateman as Michael Bluth, a widower with a 13-year-old son. Bateman’s character is forced to take over the family business when his father, played by Tambor, is arrested for questionable accounting practices.

Tambor, perhaps best known for his portrayal as sidekick Hank Kingsley on HBO’s cult hit “Larry Sanders,” most recently starred in ABC’s short-lived drama last season “That Was Then.” He was also cast in the CBS pilot “Rubbing Charlie” this year, but that show didn’t go to series — leaving the door open for Tambor to join “Arrested” full time.

Thesp’s lengthy TV career also includes “Mr. Sunshine,” “The Ropers” and “Everything’s Relative.” On film, he recently appeared in “Malibu’s Most Wanted” and “Pollock.” Tambor’s repped by Gersh.

“Arrested Development” comes from exec producers Ron Howard, Brian Grazer and David Nevins and scribe Mitch Hurwitz. Portia de Rossi, Michael Cera, Alia Shawkat, Jessica Walter, Will Arnett, Tony Hale and David Cross also star.