[1][2] Au earned a bronze medal in the Pattaya City World Cup in 2010.

[5] Au represented Hong Kong at the 2012 Summer Olympics in London, where she competed in the women's individual sabre event.

She lost in the first round to Tunisian fencer and two-time Olympian Azza Besbes, with a final score of 13–15.

[6] She reached the table of 32 at the 2014 World Championships in Kazan after defeating Venezuela's Alejandra Benítez, but lost to eventual bronze medallist Vassiliki Vougiouka of Greece.

Au is a resident athlete of the Hong Kong Fencing Association, and is coached and trained by Wong Yuet Kei.