Kim Byung-ok first established himself as a respectable stage actor before making his film debut in 2003 in director Kwak Jae-yong’s The Classic. That same year, he was cast in the acclaimed neo-noir action-thriller film Oldboy, which is the second installment of director Park Chan-wook’s The Vengeance Trilogy. In 2005, he joined its third installment titled Sympathy for Lady Vengeance, which won Best Film at the 26th Blue Dragon Film Awards. He also began appearing on the small screen, with some of his early credits being MBC’s When Night Comes in 2008 and SBS’s Fashion King in 2012. In 2014, he reunited with director Jang Jin in the films Man on High Heels and We Are Brothers. They first worked together in the 2010 comedy satire The Quiz Show Scandal. In 2018, he played Park Seo-joon’s father in the hit tvN romantic comedy What’s Wrong With Secretary Kim.