Courtney Atkinson made it a double triumph by winning the men's race.
Racing for the first time since the Beijing Games in August, Snowsill, 27, had the women's event at her mercy after opening up a 38-second lead in the swim leg.
"I did feel more nervous than I did before the Olympics and it must be that you know you've done everything possible when you're on an Olympic start-line," said Snowsill, who has eased back on her regular gruelling training schedule in the last couple of months.
The Age Reports:
"Snowsill's record fifth Noosa triumph moved her within one of Craig Walton's six successes in the event, prompting the Queenslander to joke that her coach and fiance may have to end his year-long retirement to retain household bragging rights.
"I never honestly come here and think about the number of times I've won here," said Snowsill, whose hectic post-Olympic schedule has included attending the AFL grand final as a guest of honour and being the official starter of the Gold Coast IndyCar race.
"I just come with the attitude that I love it and enjoy it and want to put my best foot forward."
Walton has often been Atkinson's Noosa nemesis.
But this time he was largely unchallenged, going past Josh Amberger early on the bike leg and powering away to win the 1.5km swim, 40km cycle and 10km run event in 1:46:38.
David Dellow was runner-up for the second year in succession in 1:48:47 and fellow Australian James Seear was third.
"I've come second here many times and it's always been in a running race by someone different," said Atkinson, who was 11th at the Beijing Olympics."