Groban will play the brother of Ed Helms' character, Andy Bernard. He will appear in an episode of the series' eighth season when Andy's family comes to visit.
Stephen Collins (Spamalot, The Loves of Anatol) and Dee Wallace will also appear as part of the family, playing Andy Bernard's parents.
Groban appeared in the London concert version of the musical Chess alongside Idina Menzel, Adam Pascal and Kerry Ellis. The singer has also appeared on screen in the first season of the Fox hit series "Glee" and, most recently, in the feature film "Crazy, Stupid, Love."
"The Office" will return to NBC Sept. 22 and airs Thursday nights at 9 PM ET.
