Peaty could not quite lower his own world record in the 100m breaststroke, having swum 56.88 seconds on Sunday in the semi-finals in Gwangju, but was still the class of the field on his way to a time of 57.14.
And it got even better for Britain as James Wilby finished strongly to claim the silver medal with a time of 58.46.
Adam Peaty, Mondiali Gwangju 2019
Image credit: Getty Images
It will take the 'perfect race' to beat Peaty in Tokyo - Wilby
That makes Peaty the first person ever to win three world titles in the 100m breaststroke, and as he looked ahead to the prospect of defending his Olympic title in Tokyo, he insists there is still more to come. He said:
My biggest demon today was going faster than yesterday. I had to be a better version of myself. Unfortunately I made a tiny, little mistake on that first length trying to force the speed a bit too much.
"The important lesson here is that I’m still learning. It’s not like I’ve gone 56 and I never have to learn again. I'm always learning, always trying to improve and thats the most important thing we can have going into an Olympics next year.
"I tried to force myself a little too much on that first 50 and I ran out a little bit of gas towards those last five metres. But it's still a 57.1. I'm still over the moon with that. We came here and did exactly what we needed to do and that was 56 and puts me in good stead for next year."
While Peaty has been the standout breaststroke swimmer in the world for half a decade now, Wilby's emergence at the highest level is more recent.
After European and Commonwealth silvers in this event last year, he added a World silver to his collection, and the 25-year-old is hoping to go one better in the 200m later in the week.
Silver medalist James Wilby of Great Britain and gold medalist Adam Peaty of Great Britain pose during the medal ceremony
Image credit: Getty Images
He added: "I focus on the 100 and 200 equally. That makes me really excited for the 200, I was really strong on the back end, that's my strength.
I'm looking forward to the 200. With that result, I couldn't be happier.
Elsewhere Ben Proud was unable to defend his 50m butterfly world title, finishing seventh in the final, with Siobhan-Marie O'Connor matching him in the 200m individual medley.
Meanwhile in the 200m freestyle, Duncan Scott booked his place in Tuesday's final, with James Guy narrowly missing out.
And finally, Molly Renshaw recorded a personal best to secure her place in the final of the 100m breaststroke.
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