Sjöström clocked 55.64 seconds to shave 0.15 seconds off the record she set in Sunday's semi-finals as she retained the world title she won two years ago in Barcelona.
“I can hardly believe it. I'm so very happy,” she told Swedish broadcaster TV4.
— Goneski (@GoodbyeChlorine) August 3, 2015
It was another great show from the 21-year-old, who in the semi-final on Sunday managed to smash the previous record set by American Dana Vollmer who swam with a time of 55.98 seconds in the London Olympics three years ago.
And the Swedish swimming champion shaved 0.15 seconds off the record on Monday.
“I was really pleased I managed to keep my nerves in check. My knees were a bit shaky just before the race. Finals are always difficult, there are more emotions going around, so I'm happy that I even managed to swim faster,” Sjöström told the Swedish tabloid Aftonbladet after the final race.
Sjöström was celebrating along with Denmark's Jeanette Ottesent, the 50 metre butterfly world champion, who took silver in 57.05 with China's Lu Ying claiming bronze with 57.48.
This was the third world record to fall in Kazan, Russia, after Katie Ledecky bettered her own 1,500 metre freestyle time in Monday morning's heats when the United States' Olympic champion swam 15 minutes and 27.71 seconds.
And it isn’t the first world record for Sjöström who last year broke the world record for 50 metres butterfly at the Swedish Championships.