The actress, who plays Mini in Skins, beat stars including Gerard Butler and Karen Gillan to take the crown.
Mavor will join previous winners including Jenni Falconer, Sharleen Spiteri and Paolo Nutini.
After scooping the prize, Mavor tweeted: "A huge thank you to those who voted for me, just won the Scottish Fashion Icon award (starts choking with shock). #amazingnight."
Meanwhile, the awards' chairman Tessa Hartmann claimed that Mavor is "brilliant at carrying off an effortless high street look".
"With her freckled complexion and luscious locks, Freya has a unique and edgy look," she said. "And as the face of Pringle, she also does designer very well too."
Mavor joined Skins as part of the third generation in the last series. The show will return with new episodes on E4 next year.
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