'Superstar' Galopin Des Champs wins back-to-back Cheltenham Gold Cups
The odds-on favourite, trained by Mullins and ridden immaculately by Paul Townend, followed up his 2023 success in jump racing's blue riband in emphatic fashion.
In second came the well backed Gerri Colombe with Grand National winner Corach Rambler in third.
Galopin Des Champs put up a performance fitting of the 100th anniversary of National Hunt's premier prize to join Best Mate and Al Boum Photo as the only horses to win the Gold Cup in successive years this century.
Winning owner Audrey Turley described watching her pride and joy repeat his heroics of last year as "terrifying".
"It does not get any easier, I will enjoy the race later on.
"I still cannot believe it. He is so special to us, he is so kind so loving."
For Mullins this was the crowning glory of a remarkable week in which the Irish master trainer notched up his 100th Festival winner on Wednesday.
It took him a long time to finally get his hands on a Gold Cup, but now he has won four of the last six editions of the great race.
"All we were worried about was the loose horse over the last two fences.
"He made one mistake early on but that was it, phew!
"To win the 100th one, the week has been so good, it's like a perfect storm," said an emotional Mullins, who also won Tuesday's Champion Hurdle with State Man.
"The third one would be the plan next year," Mullins added of Galopin Des Champs, confirming his champion will return to try to make it three in a row.
Only Best Mate (2002-2004), Arkle (1964-1966), Cottage Rake (1948-1950) and five-time winner Golden Miller (1932-1936) have succeeded in conquering jump racing's Everest more than two years running.
"He's doing everything right, and achieving more than I thought he might," added Mullins.
"You dream of those sort of things!"
Townend had Galopin Des Champs perfectly placed in third behind early leader The Real Whacker.
L'Homme Presse was prominent as one of the main dangers Fastorslow fell, the horse continuing to race riderless, posing a potential problem to Galopin Des Champs.
'Special one'
But Townend kept his cool, jumping to the front and surging up the famous Cheltenham hill to the line to beat Gerri Colombe by three and a half lengths, with a further nine and a half lengths back to Corach Rambler.
Townend commented: "He was brave the whole way around and the loose one was interfering with us a bit and it was messy.
"What he found up the straight from the back of the last — you see so many horses get to the last and don’t get up the hill. He got up the hill last year but it was a different type of ride when we conserved everything. We did it the hard way this year."
"He pulled out all the stops today. We had to go for reserves there that only the really special ones have" added the jockey who was also on-board the Mullins-trained Al Boum Photo for his two wins in 2019-2020.
The third home is now destined to try to repeat his 2023 Grand National heroics at Aintree next month.
Corach Rambler's trainer Lucinda Russell commented: "I am delighted with him, it's fantastic. That was the perfect Grand National trial, I'm so proud of him."