The Norwegian took almost a second of his previous world best clocking 45.94 seconds.
New Olympic champion Karsten Warholm hailed the best moment of his life after he shattered his own world record to win the men’s 400 metres hurdles.
He took almost a second off his previous world best of 46.70secs, set in Oslo at the start of July.
He finished ahead of the USA’s Rai Benjamin (46.17s) and Brazil’s Alison Dos Santos (46.72s) – with both coming inside Kevin Young’s time of 46.78s, which the American set nearly 30 years ago.
“It’s so crazy, it’s by far the biggest moment of my life,” said the 25-year-old Warholm.
“It defines everything, all the hours I put in, everything that my coach has been working for.
“I dream about it like a maniac, I tell you. I sleep all night on it. I spend all my time thinking about this, so just getting this last medal into my collection, it’s complete.
“I can’t sleep. I’ve spent thousands of hours thinking about this.
“I had this special feeling in my chest, you know when you are nervous. I was just thinking this is the feeling that I had when I was six-years-old. I’ve never had that feeling since I got older, but yesterday I had it.”
Warholm was leading from the start but Benjamin looked like he was about to reel him in with 90 metres to go.
Yet Warholm found an extra gear to pull away in the final 60 metres and add the Olympic title to his two World Championship crowns and European gold.
“I didn’t touch one hurdle. I was even able to find another gear coming home, so ‘wow’,” he said.
“It’s just so big. It’s almost like history here. It was the only thing missing from my collection. I had a World Championships (gold). I had European Championships, I had the world record, the European record.
“The Olympic gold medal is what everybody talks about. I knew this race was going to be the toughest of my life but I was ready.”
Athletes have already described the track as one of the fastest they have ever run on and many, including Warholm, are running with ‘super shoes’ which contain a plate and foam which helps propels them.
Warholm added: “What I can say about the shoes I have been developing in collaboration with Puma and the Mercedes F1 team is I’ve been trying to make it as creditable as we can.
“We have the carbon plate but we have been trying to make it as thin as possible. Technology will always been there but I want to keep it down to a level where we can compare results.”
Benjamin also finished behind Warholm to claim silver at the Worlds in Doha in 2019 and admitted he could not believe he did not win gold.
Benjamin said: “If you would have told me that I was going to run 46.1 and lose, I would probably beat you up and tell you to get out of my room.
“This was probably the best race ever in Olympic history. I don’t think any other race compares to what we just did.
“It’s undeniable, there’s nothing you can compare to what just happened out there.”
Dos Santos sent a new South American record and expects the trio to push and run faster.
“It was so strong, so strong, amazing. After the race, I could see the results and whoa, so, so strong. Really, really amazing,” he said.
“We want to run faster. We want to be better and this is amazing. Every guy can be better and (this race) broke the world record, it’s amazing.
“I’m so happy with this. I’m so happy because I can run with the guys. I can keep up with the guys.”