Pan touched the wall a second ahead of Australia's Kyle Chalmers, who took silver with a time of 47.48, followed by Romania's David Popovici in bronze-medal position with a time of 47.49.
Pan's time eclipsed his own previous record of 46.80 set in Doha in February. His gold-medal victory also represents a first-ever medal for China in the 100m freestyle.
Swimming's most decorated Olympian, Michael Phelps, reacted to Pan's world-record time on US broadcaster NBC, saying, "That is mind-blowing for me. I've never seen a win of that margin in that race in my career. And to go 46.4 - that's unheard of! "To be that much closer to going 45 seconds in a 100 freestyle, I can't understand that, I really can't."
On the other hand, this is the second medal in Paris for Chalmers, who also won silver in the 4x100m freestyle relay.
This also marks a second medal for Popovici following his gold-medal victory in the men's 200m freestyle.
