Sit first attempted in the 1985 Legislative Council election, the first election of the colony's legislature in the New Territories West electoral college consisting of members of the Tuen Mun and Yuen Long District Board but was lost to Tai Chin-wah.
In the 1988 Legislative Council election, he successfully gained a seat in the South Kowloon electoral college.
In June 1991, Sit put forward a motion to urge the government to resume the carrying out of the death penalty immediately.
In the council meeting on 10 July 1991, he stated that "decriminalization, of homosexuality is contrary to the moral standards of the traditional Chinese society.
The powerful Heung Yee Kuk chairman Lau Wong-fat is the brother of Kingsley Sit's wife.