Zlatan Ibrahimovic's late winner secured the EFL Cup and gave Manchester United manager Jose Mourinho his first success since his summer appointment, as brave Southampton were beaten at Wembley.
Southampton were the better side for most of this final but were left heartbroken by a controversial offside decision - and the inspiration provided by the 35-year-old Swede as he took his tally to 26 goals this season.
Saints' striker Manolo Gabbiadiani saw a goal contentiously ruled out before United took an undeserved two-goal lead through Ibrahimovic's superb 19th minute free-kick and Jesse Lingard's measured finish seven minutes before the interval.
Oriel Romeu hit the woodwork before Ibrahimovic stole in on Ander Herrera's cross three minutes from time to give United a victory that looked beyond them for long spells.
Mourinho was a subdued figure throughout this final - perhaps unable to disguise his discontent at what was a wretched performance by United for the most part at Wembley.
Inside, however, he will be ecstatic at holding silverware aloft once more, making himself a success with United in his first season at Old Trafford and performing the same trick he used at Chelsea to ease any pressure on himself and reassure supporters they have a winner at the helm.
Mourinho made it his business to target this trophy in his first season at Chelsea, beating Liverpool in the 2005 final, and it was his first success in his second spell at Stamford Bridge as Spurs were beaten here at Wembley in the 2015 final.
He is now level with Sir Alex Ferguson and Brian Clough as the most successful manager in the League Cup after his fourth triumph and takes another step on the road to rehabilitation after his sacking at Chelsea last season.
He had a warm, sympathetic exchange with his Southampton counterpart Claude Puel at the final whistle, the realist Mourinho probably realising United were outplayed for large portions of a highly entertaining final.
It will not mention that in the record books, though.
Mourinho is back among the silverware as this serial winner puts his name on United's honours board.
Zlatan the talisman
Ibrahimovic was Manchester United's man with the Midas touch, dragging them from a mire of mediocrity with his 25th and 26th goals of the season, as he secured his first success in England.
He is the leader of this developing United side, no argument brooked as team-mates stood back to let him send a 19th-minute free-kick past Southampton keeper Fraser Forster from 25 yards - although the effort was within reach of the giant stopper.
And in the closing moments, when Wembley looked for a match-winner to decide a thrilling final and prevent extra time, it was Ibrahimovic who found space among tiring Southampton defenders to power Ander Herrera's cross past Forster from six yards.
It was a goal that cements his cult status among United fans and confirms Mourinho's masterstroke in luring him to Old Trafford in one of the greatest free transfers the Premier League has seen.
United looked jaded as they were in Europa League action in Saint-Etienne on Thursday, while Saints had a two-week break - Zlatan helped refresh tired legs.
Lady luck deserts superb Saints
Southampton's players dropped to their knees in desolation at the final whistle - and who could blame them after a superb performance left them with nothing but heartbreak?
They will complain long and hard about the decision to rule out Gabbiadini's first-half effort - a poacher's strike ruled out for offside against Ryan Bertrand, who was way out of the action at the far post while the Italian was clearly onside.
They shrugged off that disappointment to restore parity either side of half-time through the predatory Gabbiadini but had no luck whatsoever, Romeu's header bouncing back off the post with David de Gea well beaten.
De Gea saved well from James Ward-Prowse and Dusan Tadic and United had several near-misses before snatching victory right at the death.
Southampton can be proud of one of the finest performances in defeat the modern Wembley has seen - but that will be no consolation to Puel's devastated players.
Manchester United match-winner Zlatan Ibrahimovic: "This is a team effort. This is what I came for - to win, and I am winning. The more I win the more satisfied I get.
"You appreciate it more the older you get. Wherever I have gone I have won. I think this is trophy number 32 for me. This is what I predicted. My friend, I keep doing it. I'm enjoying it in England."
Manchester United manager Jose Mourinho: "Honestly, Ibrahimovic won the game for us because he was outstanding. I can see a couple of performances - Pogba similar level - but he was outstanding.
"In a match where the opponent was better than us for long periods - they deserved to go to extra time - he made the difference and he gave us the cup.
"I'm a bit emotional yes. It's not easy to win titles and so many times. It's not easy to cope with the pressure I put myself under.
"It was a game I was feeling the difficulty. I want to pay homage to Southampton and what they deserve. We have the cup in our hands and probably should be in extra time."
Southampton manager Claude Puel: "We came back with quality. Perhaps we deserve better. It's football and congratulations to Manchester United and their players.
"Manolo Gabbiadini scored three good goals [including the disallowed goal]. There's a lot of disappointment of course. We had a fantastic game without the reward. I hope we can continue on this level."