The 20-year-old mixed it up with her more experienced rivals in the bunch sprint to decide the title but it was defending champion Giorgia Bronzini of Italy who triumphed on the uphill drag to the line.
She completed the 140 kilometre course in a time of 3:21:28 to edge out Marianne Vos (NED) who won in 2006 but since then has been a perennial bridesmaid with five straight silver medals. Germany's Ina-Yoko Teutenberg was third.
Hosking, who rides with pro team HTC - Highroad, says she's happy with her result and that she managed to avoid crashing during the perilous last lap.
"I was just hoping to stay upright. There were crashes left, right and centre coming down the back straight," said Hosking. "It was fast and it was dodgy but I came away with a sixth at my first world championships so I'm happy."
As has been the case with the previous races the medals have been decided in a frantic dash to the line.
"I was hoping that on that last little kick up it would break into a smaller group but it didn't and I think, you've seen in the last few races it's such a fast course. To stay away is not so easy," said Hosking. "We never wanted to do a lead out train it was more of a sit in, protect yourself and if the girls could, if they still had it in their legs, fire missiles and see if they it would string it out."
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Cycling Australian women's road coach, Martin Barras, says the team performance augers well for next year.
"When you look at where our team has been that is our best result for the last few years," said Barras. "I am not going to go and get overly excited with a sixth place, (but) the fact is it comes from a young girl it is a step in the right direction especially heading into the Olympics."
Meanwhile Amanda Spratt, team captain on the road for the Australian women, was one of those who came down in the last lap but recovered to finish the race, albeit more than two minutes after the leaders.
"The crash happened with a couple of k's to go, it was getting hectic in the finish but I'm fine and I crossed the line," Spratt said. "It was pretty chaotic. A flat course and it went so quickly. We had to be really attentive and up the front and I think we did a good job of that.
"The plan today was to be patient throughout the day and wait for the last few laps which we tried to do but nothing was sticking so in the end we put Chloe up for the sprint and she was sixth so a good result for the team."
