Henrique gave Fluminense the lead with just a minute gone, but two goals in the first three minutes of the second half by Jo and a late strike from Jadson guaranteed Corinthians the title.
The win means the Sao Paulo side have 71 points, 10 ahead of second-placed Gremio.
"We never doubted ourselves when the pressure was on," Rodriguinho said post-game. "We worked very hard for this to happen."
Corinthians last won the title in 2015 and after taking the lead five weeks into the season, they rarely looked like losing the top spot even after a stuttering run of form in September and October.
They have not shone up front, with five of the league's 20 teams scoring as many goals as the champions, but boast the best defensive record in the league.
The win was a particular triumph for first-time coach Fabio Carille.
A former journeyman defender, Carille was appointed to lead Corinthians in December after several spells as assistant manager.
(Reporting by Andrew Downie; Editing by Ian Ransom)
