The decisive score on a driving layup gave Belinelli 19 points for the game and Luol Deng added 17 as the Bulls notched their fifth win in six contests.
Joakim Noah notched 12 points and 10 rebounds for Chicago.
Deron Williams provided 24 points but misfired on a potential score-tying shot down the stretch for the Nets, who fell for the first time in three contests.
2014: The Year in Fashion [PHOTOS]
LeBron James reveals his new Nike shoes