Hii attended the National Institute of Dramatic Art for three years, and appeared in various theatre productions, before being cast in his first television role.

Hii starred as Van Tuong Nguyen in the four-part miniseries Better Man and was cast as Hudson Walsh in the soap opera Neighbours in 2013.

Hii has also appeared in the series Sisters, the romantic comedy film Crazy Rich Asians, and Marvel's Spider-Man: Far From Home.

[4][5] During his time at NIDA, Hii played in the Sydney indie-rock group RAPIDS, alongside Will Shepherd, and fellow actors Angus McLaren and Jamie Timony.

[8] Hii appeared in the lead role of Van Tuong Nguyen in SBS's four-part miniseries Better Man, which began airing from 25 July 2013.

[14] Hii went on to appear in Paul Currie's 2017 thriller film 2:22,[15] and he has a recurring role as Sam in the Australian television drama Sisters.

[15] Hii portrays Alistair Cheng in the 2018 romantic comedy film Crazy Rich Asians, based on the novel of the same name by Kevin Kwan.