Thornton has retired from professional hockey and joined the Panthers' executive staff as the Vice President of Business Operations.
Thornton on Thursday announced his intentions to retire following the 2016-17 season, George Richards of the Miami Herald reports.
Thornton scored a second-period goal during Thursday's win over Arizona.
Thornton has only dressed for 15 games this year, contributing a single assist along the way.
Thornton collected an assist in Saturday's 2-1 shootout win over the Blue Jackets.
Thornton will make his season debut Saturday afternoon against the Sabres, Joe Yerdon of NHL.com reports.
Thornton hasn't suited up for a game yet this season.
The Panthers agreed to terms with Thornton on a one-year contract extension Thursday.
Thornton tallied an assist while taking one shot on goal and posting a minus-1 in Monday's loss to Edmonton.
Thornton is likely to be scratched from Friday night's contest against the Islanders, George Richards of the Miami Herald reports.