The 17-year-old broke the previous record, set by Brazilian Cesar Cielo in 2009, by 0.05 seconds to win gold ahead of Hungarian Kristof Milak and Italian Alessandro Miressi.
Popovici, who was crowned world champion in the 100m and 200m freestyle earlier this year, becomes the youngest world record holder in the 100m freestyle.
“A fantasy now might be a 45 (second time),” he added. “Adam Peaty is a trailblazer in terms of the goals he set for himself. For others it was science fiction, but not for him.”
British swimmer Peaty set the benchmark by becoming the first man to swim the 100m breaststroke in under 57 seconds in his career – a feat he achieved when he broke his own record in 2019 .
The prospect of a new 100m freestyle record looked likely when Popovici broke the 47-second barrier for the first time in Friday’s semi-final. After his record run the following day, he was congratulated by Cielo.
“Congratulations, Popovici! Glad to have had this huge record for so long!
“There’s the new fastest man in the world in the 100m freestyle and he’s just getting started!”