Dhoni snaps Chennai's five-match IPL losing streak
Chasing a tricky 167, Chennai rode on an unbeaten stand of 57 between Shivam Dube, who hit 43, and Dhoni to achieve their target with three balls to spare at Lucknow's Ekana Stadium.
The 43-year-old Dhoni, who took over as captain from the injured Ruturaj Gaikwad in their previous defeat, strode in at number seven and smashed four fours and a six in his 11-ball knock to silence suggestions that he had lost his touch as a master finisher.
The left-handed Dube, who came in as an impact substitute for the five-time champions, got the winning boundary in his 37-ball knock.
The result snapped Chennai's streak of losses but they still remain bottom of the 10-team table with two wins in seven matches.
They started strongly with openers Shaik Rasheed and New Zealand's Rachin Ravindra, who hit 37, putting together a 52-run partnership inside five overs.
Pace bowler Avesh Khan struck first to cut short Rasheed's knock on 27 and Lucknow's ploy to bring in part-time spinner Aiden Markram worked when the South African dismissed the left-handed Ravindra.
Impact substitute Ravi Bishnoi struck with two key blows as he caught and bowled Rahul Tripathi for nine and then had Ravindra Jadeja taken at long-on for seven to dent Chennai's chase.
But Dube took charge and took Chennai over the line alongside Dhoni who walked in to loud cheers from the Lucknow crowd largely supporting Chennai.
Lucknow suffered their third loss in seven matches but can take consolation from skipper Rishabh Pant's back-to-form 63 in their 166-7 after being invited to bat first.
Wicketkeeper-batsman Pant, who had scores of 0, 15, 2, 2, 21 in his previous five innings, started cautiously with Lucknow on 23-2.
The swashbuckling left-hander played six dot balls to Afghanistan left-arm wrist spinner Noor Ahmad in the middle of his knock but finished with four fours and fours sixes in his 49-ball stay.
Pant's innings involved key stands, adding 50 with Mitchell Marsh, who hit 30 on his return after he missed the previous match, and 53 with Abdul Samad, who made 20.
Pant finally fell to Sri Lanka pace bowler Matheesha Pathirana, who took two wickets in the 20th over.
Jadeja stood out with figures of 2-24 in his three overs of left-arm spin.