Other parts in the musical will also be cast for the Broadway, touring, and international productions.
The company also presents The Mikado and The Pirates of Penzance this holiday season.
The Grammy winner joins the long-running musical for a limited time.
O'Hurley reprises his performance as silver-tongued lawyer Billy Flynn.
The performance is designed specifically for children on the autism spectrum or with other developmental disabilities.
The musical also welcomed a host of other alums to mark the milestone occasion.
Bebe Neuwirth, James Naughton, Joel Grey, and Ann Reinking will celebrate by making cameos in tonight's show.
What do the likes of Sofia Vergara and Usher have in common?