The American, knocked out in the fourth round of Wimbledon by losing finalist Sabine Lisicki, bounced back to claim her 51st match win of the year with a 6-4, 6-1 success.
Yet Williams had to recover from losing twice on her serve — including the loss of the very first game — to the home favourite before winning three break points to see out the first set.
But after overcoming that early scare, the 16-time grand slam winner cantered to a comfortable win in the second set, dropping only the penultimate game as she swept past Larsson.
The victory was Williams’ 53rd WTA win of her career and the French Open champion admitted her early exit at SW19 had fired her up for the Swedish clay court tournament.
“It was really good to come here and win after a disappointing Wimbledon so hopefully this confidence will help me for the rest of the year,” said Williams.
Larsson said: “At the crucial points I wasn’t really present, which was a shame.”