Chasing a revised target of 171 from 15 overs after a lengthy rain interruption, Chennai survived intense drama before Ravindra Jadeja sealed their victory, milking 10 runs off the last two deliveries.
The final was originally scheduled on Sunday but incessant rain forced the organisers to move the game to its reserve day.
After Chennai skipper Dhoni won the toss and elected to field, Shubman Gill walked out to bat having smashed three hundreds in his last four innings.
The opener seemed to have luck on his side too as Deepak Chahar dropped Gill, the tournament's leading scorer, at square leg when the batter was on three.
Gill also survived a run-out chance when Jadeja could not properly gather the ball before breaking the stumps.
The left-arm spinner, however, made amends in the same over.
Jadeja lured Gill (39) out of the crease and Dhoni proved age has not dulled his reflexes as the 41-year-old whipped off the bails in a flash.
Chahar also floored a return catch from Wriddhiman Saha, who smashed 54 before falling to the seamer with Dhoni collecting the top edge.
Sudharsan then tore into the Chennai attack and hit Matheesha Pathirana for back-to-back sixes in the final over of the innings to inch closer to a hundred.
Pathirana denied him the milestone but Gujarat could not be denied a 200-plus total.
Chennai's openers faced three balls before rain forced them off the field and held up play for two hours and 20 minutes.
Chasing a revised target on return, Ruturaj Gaikwad (26) and Devon Conway (47) plundered 72 runs from the first six overs before Noor Ahmad removed both in the seventh over.
Shivam Dube, who made 32 not out, kept Chennai in the race but Mohit Sharma removed Ambati Rayudu and Dhoni in successive deliveries to inject fresh drama into the contest.
Chennai needed 13 runs from the last over from Mohit, who conceded three runs in his first four deliveries.
Needing 10 off the last two, Jadeja hit Mohit over his head for a six and followed it with a boundary to seal a thrilling victory.
"I was just trying to swing hard because every ball was important," Jadeja said of the dramatic last over.
"I knew anything could happen, so I was trying to swing hard and hit it straight."