Hii was born in Kota Kinabalu, Sabah, Malaysia to a Chinese-Malaysian father from Sabah and a British mother from Manchester.[1][2] His father's family left China during the Cultural Revolution and settled in Malaysia like many others. He moved with his parents to Townsville, Queensland when he was eight. He attended the Queensland University of Technology. His early theatre work was with The Emerge Project, an arm of Switchboard Arts.[3] There he performed in a number of original productions in Brisbane by local playwrights between 2005 and 2007. From 2009 to 2011 he attended the National Institute of Dramatic Art (NIDA) in Sydney where he graduated in 2011.[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. The band released a self-titled EP in 2010.[6]
On 12 June 2013, Hii joined the cast of Neighbours as Hudson Walsh.[12] Hudson was introduced as a love interest for established character Chris Pappas (James Mason). On 20 June, Hii told Daniel Kilkelly from Digital Spy that he had been asked back to continue filming the following month.[5] After leaving Neighbours, Hii was cast as Prince Jingim in the Netflix drama Marco Polo.[13] The series was cancelled after two seasons in 2016.[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.[15][16]
From 2018 to 2019, he played Simon Van Reyk, a forensic pathologist, in the crime drama Harrow. He appeared in every episode of the first series.[15] In 2019, Hii played Brad Davis in Spider-Man: Far From Home.[17][18] He was set to have the lead role of Luen in Jane the Novela, a spin-off from Jane the Virgin, but the series was not picked up by The CW.[19] In February 2021, Hii starred as Ben Zhao in the ABC comedy-drama series Aftertaste.[20] Later that year, Hii joined the ensemble cast of The Princess Switch 3: Romancing the Star.[21]
In 2023, Hii played Dalbert Tan in the Netflix comedy drama Wellmania. The series is based on Brigid Delaney's book Wellmania: Misadventures in the Search for Wellness and was filmed in Sydney.[22] Hii also voices a rabbit called Bunniguru in the Australian animated film Scarygirl.[23]
On 28 October, Hii was named for the animated film The Pout Pout Fish.[24]