To began his acting career in TV soap operas and moved to the big screen in 2000. He is best known for playing Tsui Wai-Keung in the Infernal Affairs trilogy, as well as the role of Itsuki Tachibana in Initial D. He remarried in 2005 to Kristal Tin. In 2006, he starred in Pang Ho-Cheung's film, Isabella with Isabella Leong.
To is also an avid amateur Photographer. In 2011, To was hired as the Photographer for cantopop singer Prudence Liew's album, Love Addict. To stated that this is the first time he is paid for his photography work.
To criticized the Chinese government and proudly stated to netizens to, "Stop me from coming to the mainland if you've got guts" Chinese audiences reacted and To’s first two movies after the incident, Let Go for Love and Aberdeen, flopped at the Chinese box office. The production companies apologized and regretted casting To.
