Sjostrom only committed to racing the 100m weeks before the Games but showed she still has what it takes as she swept to her second gold medal, eight years after winning the 100m butterfly at the Rio Olympics.
Sjostrom had plenty of ground to make up at the turn but put in a sizzling final 50 metres, sweeping down lane seven to touch the wall in 52.16 seconds at La Defense Arena, 0.13 seconds ahead of American silver medallist Torri Huske.
Siobhan Haughey took bronze for Hong Kong.
Though regarded as one of the greatest swimmers of the modern era, her one Olympic gold prior to Paris seemed a disappointing return for a swimmer of her standing.
Now the Swede has the 100m gold to match her world record and more success may follow in the 50m freestyle.
Huske burnished her outstanding Olympics, having upset teammate Gretchen Walsh for the 100m butterfly gold at Paris.
The 100 and 200m runner-up at Tokyo three years ago, Haughey's bronze was her fourth Olympic medal in total and second at Paris after coming third in the 200 freestyle.
