The Kuomintang (KMT) is a major political party in the Republic of China (Taiwan). It was the sole ruling party of the country during its rule from 1927 to 1949 in Mainland China until its relocation to Taiwan, and in Taiwan ruled under martial law until 1987. The KMT is a centre-right to right-wing party and the largest in the Pan-Blue Coalition, one of the two main political groups in Taiwan. Its primary rival is the Democratic Progressive Party (DPP), the largest party in the Pan-Green Coalition. As of 2025, the KMT is the largest single party in the Legislative Yuan and is chaired by Cheng Li-wun.

The party was founded by Sun Yat-sen in 1894 in Honolulu, Hawaii, as the Revive China Society. He reformed the party in 1919 in the Shanghai French Concession under its current name. From 1926 to 1928, the KMT under Chiang Kai-shek successfully unified China in the Northern Expedition against regional warlords, leading to the fall of the Beiyang government. After initially allying with the Chinese Communist Party (CCP) in the First United Front, the party under Chiang purged communist members. It was the sole ruling party of China from 1928 to 1949 but gradually lost control while fighting the Empire of Japan in the Second Sino-Japanese War and the CCP in the Chinese Civil War. In December 1949, the Kuomintang retreated to Taiwan following its defeat by the communists.

From 1949 to 1987, the KMT ruled Taiwan as an authoritarian one-party state after the February 28 incident. During this period (known as the White Terror), martial law was in effect and civil liberties were curtailed as part of its anti-communism efforts. The party oversaw Taiwan's rapid economic development but experienced diplomatic setbacks, including the loss of the country's seat in the United Nations and loss of international diplomatic recognition to the CCP-led People's Republic of China (PRC) in the 1970s. In the late 1980s, party leader Chiang Ching-kuo lifted martial law and the ban on opposition parties. His successor, Lee Teng-hui, continued democratic reforms and was re-elected in 1996 through the first direct presidential election. The 2000 presidential election ended 72 years of KMT presidencies. The party later reclaimed power with the landslide victory of Ma Ying-jeou in the 2008 presidential election, then lost the presidency and its legislative majority in the 2016 election, but regained a legislative plurality in the 2024 election.

The party's guiding ideology is the Three Principles of the People, advocated by Sun Yat-sen and organized on a basis of democratic centralism. As the KMT supports the ROC as the only representative of China, it opposes both Chinese unification under the PRC and formal Taiwan independence. As the KMT opposes non-peaceful means to resolve the cross-strait disputes while still strongly adhering to the ROC constitution, the party favors a closer relationship with the PRC and accepts the 1992 Consensus, which defines both sides of the Taiwan Strait as "one China" but maintains its ambiguity to different interpretations. It seeks to maintain Taiwan's status quo rather than formal independence or unification.

The KMT traces its ideological and organizational roots to the work of Sun Yat-sen, a proponent of Chinese nationalism and democracy who founded the Revive China Society at the capital of the Republic of Hawaii, Honolulu, on 24 November 1894. On 20 August 1905, Sun joined forces with other anti-monarchist societies in Tokyo, Empire of Japan, to form the Tongmenghui, a group committed to the overthrow of the Qing dynasty and to establish a republic in China.

The group supported the Xinhai Revolution of 1911 and the founding of the Republic of China on 1 January 1912. Although Sun and the Tongmenghui are often depicted as the principal organizers of the Xinhai Revolution, this view is disputed by scholars who argue that the Revolution broke out in a leaderless and decentralized way and that Sun was only later elected provisional president of the new Chinese republic. However, Sun did not have military power and ceded the provisional presidency of the republic to Yuan Shikai, who arranged for the abdication of Puyi, the last Emperor, on 12 February.

On 25 August 1912, the Nationalist Party was established at the Huguang Guild Hall in Beijing, where the Tongmenghui and five smaller pro-revolution parties merged to contest the first national elections. Sun was chosen as the party chairman with Huang Xing as his deputy.

The most influential member of the party was the third ranking Song Jiaoren, who mobilized mass support from gentry and merchants for the Nationalists to advocate a constitutional parliamentary democracy. The party opposed constitutional monarchists and sought to check the power of Yuan. The Nationalists won an overwhelming majority in the first National Assembly election in December 1912.