Kang began his political career while Taiwan was still under martial law, running Huang Hsin-chieh's 1969 legislative election campaign, and serving as an independent on the Taipei City Council before contesting a legislative seat in 1972, which he won. He ran on a social welfare platform and sought to increase the representation of native Taiwanese in the government. Kang was one of two independent candidates to receive formal warnings from the Kuomintang while campaigning. The KMT believed that Kang's positions were too critical of the government, and threatened to suspend his run for office. In his first national-level election, Kang won approximately 83,000 votes. Kang started the magazine Taiwan Political Forum in August 1975. After five issues, the government banned the publication. Kang launched another periodical in March 1978 called The Eighties. Despite a moderate tone, it was also eventually shut down, returning as Asian Monthly. In 1980, he declared his candidacy for a third legislative term, winning nearly 80,000 votes. Kang ran for another term in the Legislative Yuan election of 1983, and due to the efforts of what became the New Tide faction, suffered a surprising defeat. Subsequently, he secured a visiting appointment at Columbia University in the United States. Shortly after co-founding the Democratic Progressive Party, Kang contested the 1986 Legislative Yuan elections as a representative for Taipei and finished second in the total vote count for the district, serving until 1990. In November 1988, Kang received government permission to establish the Capital Morning News. It began in May 1989 and ran until August 1990 when it was shuttered due to lack of funds. In October, he was named to the National Unification Council, but missed the first meeting, as the Democratic Progressive Party had at first chosen to boycott the group over concerns about its name. Kang had been active in a preceding committee, the National Affairs Conference. After a stint in the National Assembly, he was appointed to the Control Yuan in 1993, and as a result, Kang's DPP membership was suspended. While a member of the Control Yuan, Kang played a lead role investigating the murder of and the related. In 1998, Kang participated in the follow-up meetings taking place after the initial Wang–Koo summit in 1993. Throughout 2002, it was reported that Kang would assume a deputy ministerial position at the Ministry of National Defense, and he eventually took office on 31 May. After two months with the MND, Kang's DPP membership was restored. In October, Kang visited the Pentagon in his official capacity, becoming the first Taiwanese official to be received in Washington D.C. since the termination of official relations in 1979. Kang was named the head of the National Security Council in February 2003, and during his tenure adopted a direct management style designed to enhance transparency within the institution. In June, Kang tried to promote longtime aide Huang Tsai-tien to rear admiral. The proposal was blocked, as Huang did not fulfill the requirements for promotion. Soon after, media reports alleged that Kang's leadership caused many others at the agency to resign, a claim he rejected. In August, another of Kang's hires was forced to resign, as she had been linked to entrepreneurship opportunities in China. Shortly after leaving the National Security Council, Kang was named a senior adviser to President Chen Shui-bian. By 2006, he had left that position. After leaving government service, Kang became the president of the Foundation for Asia-Pacific Development.
