In 2003, William participated in the International Chinese New Talent Singing Championship Hong Kong regional finals and won several awards.

[1] He was then signed by Emperor Entertainment Group (EEG) as a new talent and started appearing in TV shows as a host.

[4] From 2010 to 2013, William released four more albums, namely Do You Wanna Dance (2010), Heads or Tails (2010), WOW (2011) and Pop It Up (2013).

[6] In 2016, William released the single "Plan W", which topped local music charts and reached ten million downloads in 12 hours.

[12][13] In 2020, his second solo tour originally scheduled to kick-start in Guangzhou on 14 March 2020 was postponed due to the global COVID-19 pandemic.

[15] William then starred in the Hong Kong-Chinese film As the Light Goes Out (2013), which won him the Best Supporting Actor award at the Macau International Movie Festival for his performance.

He filmed his first Chinese drama, The Four, an adaptation of Woon Swee Oan's novel Si Da Ming Bu.

[25] William gained a surge in popularity for his role as Fo Ye,[26] and was named the "Person of the Year" at the iQiyi All-Star Carnival.

The same year, he starred alongside Jessica Jung in the romantic comedy film I Love That Crazy Little Thing and featured in Guo Jingming's fantasy blockbuster L.O.R.D: Legend of Ravaging Dynasties.

[42] In 2020, he was a mentor in comedian talent scouting show Gagman and starred in reality sales-marketing series "Fourtry Season 2".

In 2023, he took part as a regular in reality variety shows Run for Time Season 3 and Fairy Tale - Welcome to Star Village.