Au Yeung took up fencing with some of her friends. She joined the national team in 2004 after being noticed by a national coach at an inter-school competition. She won a team silver medal at the 2005 Asian Championships and a team bronze medal at the 2006 Asian Games. She won a silver medal in the 2010 Pattaya City World Cup. In the 2011 Summer Universiade she reached the semifinals after defeating Romania's Mihaela Bulică, then lost to another Romanian, Bianca Pascu, and came away with a bronze medal.