The 19-year-old actor and model — who appeared on the cover of Vogue Australia in July - posed on the blue carpet in a stunning sleeved floral dress by Sydney-based designer Zimmermann.
Her hair was in a messy up-do and she toughened up the feminine look with her leg tattoos (teamed with strappy heels, of course).
Earlier, British singer Rita Ora turned heads with her yellow hair.
The RIP singer was one of the first to walk the blue carpet at the Galen Center before she performed on stage.
Rapper French Montana and former One Direction member Louis Tomlinson also performed at the 19th annual show, which will honour Malibu singer Miley Cyrus and Bruno Mars.
Cyrus, who is engaged to Australian actor Liam Hemsworth, is receiving the ceremony’s highest gong, the Ultimate Choice Award.
It marks Cyrus’s involvement with the Teen Choice ceremony for more than a decade, the New York Post reports.
They’ve given her 18 awards so far, and she is nominated for another four today.