Sinner bested the 24-time Grand Slam champion 7-6 (4), 6-3 in an hour and 37 minutes, never facing a break point throughout the outdoor hard-court tournament.
The Italian delivered eight aces and 22 winners compared to Djokovic’s four aces and 12 winners.
Djokovic was aiming for his 100th tour-level title and his fifth in Shanghai. Only two legends in men’s tennis, Jimmy Connors with 109 titles and Roger Federer with 103, have reached the century mark.