Orb, ridden by Joel Rosario and prepared by homebred trainer Shug McGaughey, won the 139th Kentucky Derby at a wet and muddy Churchill Downs on Saturday.
After settling near the rear of the field in the sloppy conditions, Orb steadily worked his way into contention, then pinned back his ears and sprinted to the front at the iconic Twin Spires and kicked clear to win the $2 million, 1-1/4 mile classic.
Golden Soul, a long shot who enjoyed a trouble free journey along the rails, finished gamely to grab second while Revolutionary was third in the 19-horse field.
"It's awesome, to win the Derby, it's like a dream," said Rosario, who had never won the Derby before but won this year's $10 million Dubai World Cup, the world's richest race, on Animal Kingdom.
"I was so far behind I just let (Orb) be calm and relaxed, then I steered him to the outside because I didn't want to get blocked. He did the rest."
Normandy Invasion finished fourth after leading the field into the final stretch while Mylude was fifth under the guidance of Rosie Napravnik, marking the best finish in the revered race by a female jockey.
Orb, who was bred and trained in Kentucky, emerged as the horse to beat in the annual Run for the Roses after winning his four previous races, including the $1 million Florida Derby, one of the key lead-up events.
He was initially installed as the 7-2 favorite despite drawing gate 16 at Wednesday's post-position draw but began to drift in the betting as the race approached.
Only a late surge of money saw him retain his place as outright favorite, at odds of 5-1, just a point ahead of Revolutionary, the Louisiana Derby winner.
"Obviously it's a huge, huge thrill for me," said McGaughey, a 62-year-old trainer who was born and raised in Kentucky.
"It's a race I've always wanted to win, a race I've always wanted to compete in if I thought I had the right horse, and finally today we had the right horse."
McGaughey had already won most of America's biggest races and been inducted into the Hall of Fame almost a decade ago, but the Kentucky Derby had always eluded him.
"I don't know what it will be like tomorrow morning when I pinch myself and figure all this out," he said.
"The way it's going to change my life is I'm not going to have to worry about it anymore, because I've worried about it for a while."
Rosario, a 28-year-old jockey born in Dominican Republic, patiently held his mount back in the early stages of the race, which was held on a track drenched by hours of heavy rain.
He resisted the temptation to look for a shortcut on the fence, opting instead to keep Orb on the outside, where he continued to make ground.
It was a tactic that paid off when the early leaders, who had set off at a cracking pace, started to fade, Orb was perfectly positioned to make his charge.
Orb swept past a dozen rivals on the back straight and was within sight of the leaders round the final turn. As the crowd of 151,616 let out a deafening roar, he made his move, charging down the center of the track and holding off all his challengers.
Golden Soul, a 31-1 chance ridden by Robby Albarado, also came from behind to take second for his owner, Canadian diamond magnate Charles Fipke.
Revolutionary was one of five runners in the race trained by Todd Pletcher. He was ridden by Calvin Borel, a three-time winner of the Kentucky Derby, who stuck to the fence but could catch the winner.
The lone international entrant, Irish galloper Lines of Battle, finished seventh, while Goldencents (7-1), prepared by last year's winning trainer Doug O'Neill, weakened badly to cross the line 17th under jockey Kevin Krigger, who was bidding to become the first African-American jockey to win the race in more than a century.
In keeping with tradition, the race was preceded by the singing of "My Old Kentucky Home" as a huge crowd packed into the Louisville course, dressed in an array of outfits and sipping on mint julep drinks.
But no sooner had Orb, who paid $12.80 for a $2 bet, been draped in the traditional garland of red roses, than talk turned to the future.
The bay colt now has the chance to win the coveted Triple Crown. The second leg, the Preakness Stakes, will be held at Maryland later this month followed by the Belmont Stakes, in New York in June.
The last horse to win the Triple Crown was Affirmed in 1978.
"I still think there's something more there, I don't think we've bottomed out," said McGaughey. "I think we've got our hands on a pretty special horse."
(Reporting by Julian Linden in New York, editing by Gene Cherry)