Kwok's father was an officer in the National Revolutionary Army of the Republic of China. Kwok stayed in Chungking during the Japanese occupation of Hong Kong, and returned after Japan surrendered in 1945. After studying in Shau Kei Wan for primary school and at Catholic Ming Yuen Secondary School in Rennie's Mill, Kwok went to National Taiwan University and graduated with Bachelor of Laws. Kwok then worked in Hong Kong's judiciary.
