Thorn, who takes over the duties from Ed Stefanski, had been the Nets' president for 10 years before leaving last month.
Stefanski will continue to serve as the Sixers' general manager, the team said on its website (http://www.sixers.com).
He had been both president and general manager since 2007 and had served as Thorn's general manager in New Jersey for nine seasons.
(Reporting by Gene Cherry in Raleigh, North Carolina. Editing by Steve Ginsburg)