He shot to a time of 50.68 seconds, beating his previous record of 51.41, which he set at the US Championships last month.
McLaughlin edged past her competitors to take the lead, edging out Dutch runner Femke Bol and former world champion Dalilah Muhammad, who took silver and bronze in 52.27 and 53.13 respectively.
McLaughlin’s supreme performance set a string of records for the American last year.
He ran an astounding 51.90 seconds in the 400m hurdles at the U.S. Olympic trials last summer, according to the World Athletics website.
McLaughlin set another world record and won gold with a run of 51.46 seconds at the 2020 Tokyo Olympics.
‘Faster and faster’
McLaughlin became the first woman to finish the 400m hurdles in under 51 seconds.
“The weather is absolutely incredible and the sport is getting faster and faster,” he said after the race, according to the World Athletics website. “Just figuring out what barriers can be broken. I just get faster from there.
“I ran the race the way Bobby (Kersee, his coach) wanted. Coming home I knew if I just kept my cadence up and stayed in the stride pattern, we could do it and it happened.
“The level of the 400m hurdles is definitely improving. We have a full group of girls that are ready to push our bodies to the next level and we are seeing the times drop,” McLaughlin added.
Olympic bronze medalist Bol said: “I raced against the best in the world, Sydney is very strong.
“She was so far ahead at the end, so I always doubted if she had really run a good race because it felt so good. Then I saw the time and I was like, ‘Wow.’ It’s amazing to be a part of it and to come out second in such a race,” added Bol.
Muhammad, who won silver in the same event at Tokyo 2020, said he had “mixed emotions” about his performance.
“It’s great to get a medal, but I’ve come into these championships with the strength of having always medaled at any championship, despite injuries. But as a competitor, you always want more.”