One For Arthur became only the second Scottish-trained winner of the Grand National after a four-and-a-half-length victory at Aintree.
The 14-1 shot, ridden by Derek Fox and trained by Lucinda Russell, charged clear to finish ahead of Cause Of Causes (16-1) and Saint Are (25-1).
Jockey Fox only returned to riding this week having broken a wrist and a collarbone in March.
The 8-1 favourite Blaklion, who led for much of the contest, was fourth.
Gas Line Boy - a 50-1 outsider - was fifth with Becher Chase and Grand National Trial winner Vieux Lion Rouge (12-1) sixth.
- 'One For Arthur's National win a triumph to treasure'
- Full racecard result
- Bookies count cost of National win
The win was just the second by a Scottish-trained horse since Rubstic's victory in 1979.
In sunny conditions in Liverpool, 19 of the 40 horses finished the race, with Aintree reporting afterwards that all runners came back safely.
Fox, who broke his wrist and dislocated a collarbone just over a month ago, told BBC Radio 5 live: "It's the best feeling I've ever had. He's just such a brave horse. It's a sign of a true racehorse to win the Grand National. It's unbelievable.
"I was injured on 9 March, I got a heavy fall on the novice chase and that was four weeks ago on Thursday.
"This is the best feeling I have ever had or probably ever will have and I want to take most of it in. I don't often get a chance to ride a horse as good as that."
Russell, whose partner and assistant is former champion jockey Peter Scudamore, is the fourth woman to train a Grand National winner after Jenny Pitman, Venetia Williams and Sue Smith.
"He's amazing," she said. "He's improved every time. I kept thinking barring accidents, he would win the National and he has.
"Together [Peter and I] we have had good and bad times but the horses are all back in form now.
"He's done us proud, he's done Scotland proud and he's done everyone at the yard proud."
Two Golf Widows enjoy 'fantastic journey'
The winning owners are Deborah Thomson and Belinda McClung, who go under the name 'The Two Golf Widows'.
Thomson said: "I just can't believe it. It's been an absolutely amazing day. Arthur just cruised that race, Derek rode so well and I'm just a bit lost for words really.
"He's given us a fantastic journey."
McClung added: "I thought this morning, it's baking hot so there's no pressure now, he's not going to win on that ground but I have to say he's just shown his class today.
"He's amazing and he got a great ride."
Two false starts and a dramatic finish
Aintree stewards referred 31 of the 40 Grand National jockeys, including winner Fox, to the British Horseracing Authority after it took three attempts to get the race started.
Runners and riders were twice called back after some set off before the starter was happy an orderly line had formed.
Nine jockeys were exonerated, but the starter reported the rest to the stewards, saying they approached the tape before the flag was raised.
The BHA will consider whether to take further action.
After the false starts, the race eventually got under way but began with exits at the first fence for Vicente (16-1) and Cocktails At Dawn (33-1).
Definitly Red (10-1), who was an impressive winner at Doncaster last month for Brian Ellison, was pulled up at the Canal Turn, with jockey Danny Cook revealing that an awkward landing sent his saddle slipping round and the pair out of the race.
The ending was equally eventful as a collision coming over the last saw Blaklion overtaken before One For Arthur showed greater speed to hold off the valiant Cause Of Causes.
Jamie Codd, rider of the Gordon Elliott-trained Cause Of Causes, said: "He's a fantastic little horse. I thought I had half a chance at the back of the last, but the winner has won quite well on the day.
"My horse has galloped all the way to the line. He's an incredible little horse. I'm disappointed I didn't win, but he's run a great race."
BBC horse racing correspondent Cornelius Lysaght
The cheers may have been loudest for this emphatic winner around Lucinda Russell's base near Kinross, but they will echo across jump racing's north of England and Scottish circuit.
Jumping in the north is regularly - and correctly - portrayed as the poor relation to its cousins in the south. The bigger investors tend to stay away.
However, three Grand National runners - also Definitly Red and Highland Lodge - boded well, and One For Arthur, who's done a majority of his racing at places like Kelso, Carlisle and Ayr, has been invaluable to show it can be done perfectly well north of the Trent as well; will those biggest investors take notice?
Meanwhile, talk will turn to Aintree 2018 and a possible repeat; he'll have more weight, but as an eight-year-old can he be expected to improve again?