Tsai caught the world's attention last January when she rebuffed President Xi's remarks about plans to "re-unify" Taiwan and China by insisting that the Taiwanese people would never willingly accept reunification with Beijing. She also insisted that the threat of a Chinese invasion of Taiwan was "growing every day."
Taiwan's president triumphed over two challengers in Saturday's election: Han Kuo-yu of the rival Kuomintang, the party of Taiwan's founder, Nationalist General Chang Kai Shek, and James Soong of the smaller People First Party, according to final vote tallies seen by the Associated Press.
With nearly all votes counted, Han has reportedly called Tsai to concede.
Han, the KMT candidate, was said to run a "Trump-like" campaign seeking to capitalize on populist anger.
By winning reelection, Tsai as dealt a serious blow to the Kuomintang, which had ruled over Taiwan for most of its history as a quasi-nation independent of the mainland. Han, the KMT candidate, had pushed for friendlier ties with Beijing.