Geraint Thomas became the third Briton to win the Tour de France when he crossed the finish line in Paris.
The Team Sky rider, 32, follows Sir Bradley Wiggins in 2012 and four-time Tour champion Chris Froome as Britain celebrates a sixth win in seven years.
Alexander Kristoff won the final sprint finish on the Champs-Elysees as Thomas crossed the line arm-in-arm with Froome after three weeks of racing.
He beat Dutchman Tom Dumoulin by one minute 51 seconds, with Froome third.
The Welshman, who rode in support of Froome in each of his four wins, had built up that lead over the previous 20 stages and Tour convention dictates that the yellow jersey is not challenged on the final stage.
"When I rode on the Champs-Elysees for the first time in 2007, that was insane - just to finish the race and just to be a part of it," Thomas told ITV.
"To now be riding round winning it is just incredible. It's just a whirlwind. I seem to be floating around on cloud nine.
"Maybe when I'm 70, sat in a corner of a pub telling some 18-year-old what I used to be, it will sink in. It's incredible, the stuff of dreams."
- 'So tired he rang the doorbell with his head' - Thomas' journey to Tour champion
- Thomas became 'clear' team leader after winning stage 11 - Froome
- BeSpoke at the Tour podcast: A special day on the Champs-Elysees
- Stage by stage - how Thomas won the Tour
Froome was heavy favourite to become the fifth rider to win a record-equalling fifth Tour de France title. He came into the race as defending champion and holder of all three Grand Tour titles, having won the Vuelta a Espana last September and the Giro d'Italia in May.
However, he was only cleared to race the week before the Tour started, after his anti-doping case was dropped by cycling's world governing body, the UCI.
The 33-year-old was under investigation after more than the permitted level of legal asthma drug salbutamol was found in his urine during his Vuelta victory.
But his hopes of matching Eddy Merckx's record of four consecutive Grand Tour victories were ended in the Pyrenees mountains in the final week as Thomas proved the strongest rider.
A procession into Paris
The final 116km stage began in Houilles, to the north-west of Paris, and the riders took a leisurely pace into the capital before embarking on eight laps of the city centre.
Team Sky led the peloton into Paris, having allowed France's Sylvain Chavanel to ride clear for one lap in his final Tour in recognition of his achievement of completing a record 18th race.
Six riders attacked off the front of the peloton and built an advantage of about 45 seconds, but they were eventually reeled in on the final lap, with 6km remaining.
World champion Peter Sagan's Bora-Hansgrohe team-mates did the bulk of the chasing, hoping to help the winner of the green points classification jersey to a first win in Paris, but Norwegian Kristoff outsprinted Frenchman Arnaud Demare and Germany's John Degenkolb after Yves Lampaert's late attack failed.
Thomas rode over the line a few seconds later, alongside Froome, the man he dethrones as champion.
Thomas' Tour pedigree
Thomas' victory comes in his ninth Tour, one fewer than the record for most appearances before winning, held by 1980 winner Joop Zoetemelk of the Netherlands.
Thomas first rode in the Tour in 2007, when he finished 140th of the 141 finishers.
Like many British riders, he raced on both the track and the road in the early part of his career, winning two Olympic and three world team pursuit titles on the track between 2007 and 2012.
His sacrifice in helping Froome win four Tours has meant Thomas' best finish before this year was 15th.
He has also been dogged by bad luck. He fractured his pelvis on stage one in 2013 but rode the remaining 20 stages to help Froome win; in 2015 he crashed head first into a telegraph pole; and in 2017 broke a collarbone on stage nine.
This year, he has ridden a near faultless race to cement his place among Britain's greatest cyclists.
Cavendish leads praise for 'G'
Mark Cavendish, a former Team Sky and Great Britain team-mate of Thomas, said he was "so, so proud" of his achievement.
Asked if he ever thought Thomas could win a Grand Tour, Cavendish, who has won 30 Tour de France stages, told BBC Sport: "Recently, yes. But there is a definite hierarchy in Team Sky so I didn't know if he'd get the opportunity.
"If they (Team Sky) had said to Geraint 'right, now you've got to work for Froome' he'd have done it. That's the kind of guy he is. That's what is special about him and why he deserves the win.
"He's the most loyal guy you'll ever meet. He's incredible. I love him. I'm so, so proud of him."
Peter Kennaugh, another former Team Sky and GB team-mate, added: "It's incomprehensible. It's 'G' and he's won the Tour de France. I can't imagine how he feels. I'm just so proud of him."
Ex-Team Sky team-mate Ben Swift, who shared a house with Thomas in Manchester, said: "It's amazing to see. We've grown up together, been at the British Academy together, lived together, so to see him do this is incredible."
Three-time world team pursuit world champion Dani Rowe said: "I did see him as a Tour winner. He's one of the most hard-working riders I've ever come across, so I think he deserves this more than anyone."
Former British cyclist Chris Boardman, who won three Tour stages and wore the yellow jersey, said: "He's the most popular winner for years. No disrespect to those who have gone before him but he's always laid it down for someone else and sacrificed himself for someone else."
The stages that defined Thomas' victory
Thomas went in to this year's race saying he was hoping to challenge team leader Froome.
He told BBC Sport: "The team have said with the way I've been riding they're confident to give me that role of a back-up guy and to race at least until the first rest day (after stage nine)."
He was second after stage nine and took hold of the race leader's yellow jersey on stage 11.
- Stage 3: Team Sky finish second in the team trial to propel Thomas up the standings to third, three seconds adrift of race leader Greg van Avermaet.
- Stage 6: A tactically aware Thomas picks up two bonus seconds near the finish to move himself up to second overall.
- Stage 11: Thomas attacks with 6km remaining on the final ascent to the summit finish at La Rosiere in the Alps to finish 20 seconds ahead of Dumoulin and Froome and take the race leader's yellow jersey.
- Stage 12: Another late surge sees Thomas become the first British rider to win on the fabled Alpe d'Huez as he again leaves Dumoulin and Froome in his wake to cement his position as a real threat in the race. "There wasn't a chance in hell I was going to win," Thomas said. "I just kept following Dumoulin and Froome. Can we just go to Paris now?"
- Stage 17: Into the Pyrenees and an attack in the closing few hundred metres helps Thomas finish third to put another nine seconds into Dumoulin as Froome falters on the final climb, finishing 48 seconds behind his team-mate.
- Stage 19: The final stage in the mountains and Thomas follows the attacks of all his rivals before sprinting to second on the stage to pick up more bonus seconds and move two minutes five seconds clear. He has accrued 33 bonus seconds, 21 more than Dumoulin.
- Stage 20: Dumoulin wins the time trial, beating Froome by one second, but Thomas finishes third on the stage to maintain a lead of one minute 51 seconds.
How did the other Britons fare?
Mark Cavendish set out looking to make further inroads in Eddy Merckx's record of 34 Tour stage wins, but the Dimension Data rider was unable to add to his tally of 30. He missed out on the early sprint stages and was eliminated when he missed the time cut on the mountainous 11th stage.
Mitchelton-Scott rider Adam Yates won the young rider classification in 2016 and was tipped to go well this year, but dehydration in the Alps - he was dropped on the way to La Rosiere on stage 11 and again on the next stage to Alpe d'Huez - cost him dearly. To end a miserable Tour, he crashed while leading on stage 16 and finished third.
The third British rider in Team Sky's squad, Luke Rowe, finished 130th - almost four hours behind the winner - but his sacrifices to help compatriot Thomas win will live long in both their memories.
Who won green, polka dot and white jerseys?
Three-time world champion Sagan romped away with the green points jersey, which rewards consistently high finishes on each stage. It is a joint record sixth victory in the classification for the Slovak, matching Germany's Erik Zabel.
Sagan won three stages and finished in the top 10 on nine others to amass 477 points, more than double Kristoff in second.
The polka dot 'king of the mountains' jersey was claimed by Julian Alaphilippe, who comfortably beat fellow Frenchman Warren Barguil.
Another home rider, Pierre Latour, won the white jersey awarded to the best young rider (under the age of 26).
1. Geraint Thomas (GB/Team Sky) 83hrs 17mins 13secs
2. Tom Dumoulin (Ned/Team Sunweb) +1min 51secs
3. Chris Froome (GB/Team Sky) +2mins 24secs
4. Primoz Roglic (Slo/Team LottoNL-Jumbo) +3mins 22secs
5. Steven Kruijswijk (Ned/Lotto NL-Jumbo) +6mins 8secs
6. Romain Bardet (Fra/AG2R La Mondiale) +6mins 57secs
7. Mikel Landa (Spa/Movistar) +7mins 37secs
8. Daniel Martin (Ire/UAE Team Emirates) +9mins 5secs
9. Ilnur Zakarin (Rus/Katusha-Alpecin) +12mins 37secs
10. Nairo Quintana (Col/Movistar Team) +14mins 18secs
Stage 21 result:
1. Alexander Kristoff (Nor/UAE Team Emirates) 2hrs 46mins 36secs
2. John Degenkolb (Ger/Trek-Segafredo) same time
3. Arnaud Demare (Fra/Groupama-FDJ)
4. Edvald Boasson Hagen (Nor/Team Dimension Data)
5. Christophe Laporte (Fra/Cofidis)
6. Maximiliano Richeze (Arg/Quick-Step Floors)
7. Sonny Colbrelli (Ita/Bahrain-Merida)
8. Peter Sagan (Svk/Bora-Hansgrohe)
9. Andrea Pasqualon (Ita/Wanty-Groupe Gobert)
10. Jasper de Buyst (Bel/Lotto-Soudal)