Tony McCoy ended his Grand National jinx in superb style as he claimed victory at the 15th attempt on board 10-1 joint favourite Don't Push It.
Don't Push It jumped the last with Black Apalachi but pulled away down the straight to give trainer Jonjo O'Neill and owner JP McManus their first wins.
Black Apalachi (14-1) was five lengths behind, ahead of State of Play (16-1).
Joint favourite Big Fella Thanks, with Barry Geraghty replacing injured jockey Ruby Walsh, finished fourth.
McCoy, the 14-time champion jockey, has ridden more than 3,000 winners, but Grand National victory had remained frustratingly elusive, with three third-place finishes his best efforts before Saturday.
McCoy thanks trainer
The 35-year-old Northern Irishman, who first rode the National in 1995, was close to tears as he spoke to BBC Sport after crossing the finish line of the four-and-a-half-mile marathon.
"I'm being a big wuss. It means everything to me to win the Grand National.
"I've won lots of big races and I'm supposed to be a good jockey, but to not win the Grand National would be a bit of a negative on the CV."
Trainer O'Neill, who never won the race as a jockey, also celebrated an emotional win.
Walsh, twice a winner of the National, suffered a broken arm in a heavy fall on Celestial Halo in the Dick Francis Aintree Hurdle earlier on the card.
He was replaced by Geraghty, with Richard Johnson taking over on Geraghty's original mount Tricky Trickster. But Big Fella Thanks nonetheless went out as joint favourite along with Don't Push It, after a late flurry of bets on McCoy's mount.
Grand National - closing stages (UK users only)
And there was more drama at the start as King Johns Castle, ridden by Paul Carberry, refused to race, despite stewards holding the start to allow the horse to settle.
As Conna Castle made the early running, McCoy bided his time on the first circuit.
But he later revealed that during that first circuit he had an inkling that this could be his day.
"I had a strange feeling early on that the horse was enjoying what he was doing," McCoy told BBC Radio 5 live on Sunday.
"But you have to keep your concentration and the more the race went on, the more I got the buzz."
And with four fences of the 30 to go, he surged to the front and eventually won by a decisive margin.
Black Apalachi, trained in Ireland by Dessie Hughes, was left trailing in his wake. His jockey Denis O'Regan said: "He was a bit keen early on but once he settled into a lovely rhythm he was fantastic. It's a pleasure to ride a horse like him round here."
Paul Moloney's mount State of Play, went one better than his fourth position last time round for Welsh trainer Evan Williams.
Moloney said: "It was a serious run from a serious horse who has been very good to me and he might win it next year."
Hello Bud, ridden prominently throughout by 17-year-old Sam Twiston-Davies, was in contention at the second last but faded to finish fifth.
Nina Carberry, attempting to become the first woman to win the race on Character Building, finished in seventh, behind the well-backed Snowy Morning.
Last year's winner Mon Mome was going well when he fell at the 26th fence.
Preists Leap was the last of 14 finishers, by which time celebrations in the Don't Push It camp were well under way.
Grand National - how they fared
McManus, a former joint-owner of Manchester United, paid tribute to racing manager Frank Berry, who found the horse in Listowel.
"I don't think without Frank we would have had the horse," he said.
"Full marks to Jonjo and the team as he's been a difficult horse down the years to keep right and keep his mind right."
McCoy waited until Thursday to choose Don't Push It ahead of Can't Buy Time, who unseated jockey Richie McLernon at the eighth fence.
"My trainer put me on the right one if truth be known," he said.
"I asked him to toss a coin and I think he tossed it a few times until he got Don't Push It. I couldn't have picked it, but Jonjo was very adamant and I didn't argue with him.
"If you get enough goes at something and you keep going, once you're in there you've always got a chance.
"I'm delighted for JP (McManus) as he's the best supporter this game has ever had and ever will have, and I'm very privileged to ride a Grand National winner in his colours."
McCoy's victory was a huge blow to bookmakers. Don't Push It was backed down from 20-1 on Saturday morning to 10-1.
"It has cost us millions," said David Williams from Ladbrokes bookmakers. "We've feared this day for 15 years and our worst nightmares have just been realised. Punters never lost faith in the champ."
Williams estimated the betting industry in Britain would have lost £50m on the race but for McCoy it was back down to earth with a bump on Sunday, with the 35-year-old fulfilling his obligations with three rides at Southwell.
And as he explained on Sunday, he's already thinking of next year's race.
"I'm the type of person that lives in the future," said McCoy.
"I'm riding at Southwell today and I'd love to win the Grand National again next year."
Grand National result:
1. Don't Push It (Tony McCoy) 10-1 joint favourite
2. Black Apalachi (Denis O'Regan) 14-1
3. State of Play (Paul Moloney) 16-1
4. Big Fella Thanks (Barry Geraghty) 10-1 joint favourite
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