Debutant Collin Morikawa held off a charge from Jordan Spieth to win the 149th British Open by two shots after a scintillating Sunday's action at Royal St. George's.
At just 24, Morikawa claimed his second major thanks to a bogey-free round of 66 to finish on 15 under par.
"This is by far one of the best moments of my life," said the world number four, who handled the pressure with ease in front of crowds of 32,000 fans on the Open Championship's return after a two-year hiatus caused by the coronavirus pandemic.
"To see some of the best crowds I've ever seen, I look forward to my trip every year to the British Open to see you guys."
The American had never even played in links conditions until last week's Scottish Open when he tied for 71st, the worst finish of his professional career.
But the world number four showed no sign of inexperience as he revelled in the sweltering conditions as temperatures hit 30 degrees celsius in Sandwich on England's south-east coast.
"I've had belief in myself since turning pro that I can do it," added Morikawa, who is the first man to win two majors in his first eight appearances since 1934.
"When it's coming to these tournaments, courses and styles that I have never played, I do my homework Monday to Wednesday to know what I need to do."
Overnight leader Louis Oosthuizen's bogey at the fourth allowed Morikawa to move into a share of the lead and he never looked back after a two-shot swing at the par-five seventh.
Oosthuizen, who finished at 11 under in a share of third with Jon Rahm, twice found bunkers around the green to drop another shot.
Meanwhile, Morikawa drained the first of three consecutive birdie putts to hit the turn at 14 under.
The 2020 US PGA champion needed his putter to stay hot on the back nine just to save par at 10, 11, and crucially at 15 with Spieth breathing down his neck.
But by that time, he had moved to 15 under with another long-range putt at the par-five 14th.
Three solid pars coming home made Morikawa the first British Open debutant to win since Ben Curtis' shock success also at Royal St. George's 18 years ago.
Spieth was left to regret his sloppy finish to Saturday's third round when bogeys at the final two holes saw him start day two behind Morikawa.
"The finish yesterday was about as upset as I've taken a finish of a round to the house," said the three-time major winner.
"I walked in and said: 'Is there something that I can break? I knew that was so important because I would have been in the final group."
The 2017 British Open champion slipped back to seven under after dropping another two shots at the fourth and sixth before roaring back.
An eagle at the seventh launched Spieth's challenge and he completed the final 12 holes in six under par with further birdies at the ninth, 10th, 13th, and 14th.
"I'm proud of going six-under in the last 12 in this golf tournament and putting some pressure on Collin," added Spieth. "I did all I could."
But Morikawa never flinched to become the first man to win two majors on debut at that event.
Rahm also showed why he was the pre-tournament favourite after landing his first major at last month's US Open with a brilliant 66 that could have been far better but for a better day with the putter.
The Spaniard needed an eagle on seventh to get him going but just ran out of holes after four consecutive birdies between 13 and 16.
Oosthuizen's wait for a second major goes on as he finished in the top three for the eighth time since his sole success in the 2010 British Open at St Andrew's.
South African Dylan Frittelli, who was only called into the field as 11th reserve on Monday, finished fifth on nine-under.
World number one Dustin Johnson finished in a tie for eighth on seven under.