Taiwan's independence-leaning opposition leader Tsai Ing-wen won the island's presidential election today after the ruling party admitted defeat, a result likely to usher in a new round of uncertainty with giant neighbour China.

A source with Tsai's Democratic Progressive Party (DPP) told Reuters that the party was working on Tsai's victory speech. She was expected to speak within the hour.

"Eric Chu disappointed everyone. We lost. The Nationalists have been defeated," Nationalist presidential candidate Chu said, surrounded by sombre-looking supporters, some in tears, adding he had also resigned as party chairperson.

Taiwan Premier Mao Chi-kuo also resigned, following the defeat, the cabinet said. The resignation is pro forma in Taiwan for a ruling party when it loses a major election.

Outside DPP headquarters, supporters cried, but for joy.

"The Taiwanese people despise the party that gets too close to China," said Jeff Chang, 35.

Anita Lin, 37, said she was "thrilled". "Taiwan's future is not in China. It's in the world."

Tsai will be thrust into one of Asia's toughest and most dangerous jobs, with China pointing hundreds of missiles at the island, decades after losing Nationalists fled from Mao Zedong's Communists to Taiwan in the Chinese civil war.

She will have to balance the superpower interests of China, which is also Taiwan's largest trading partner, and the United States with those of her freewheeling, democratic home.

Tsai risks antagonising China if she attempts to forcefully assert Taiwan's sovereignty and reverses eight years of warming China ties under incumbent President Ma Ying-jeou of the Nationalists, whose forces retreated to Taiwan in 1949.

There was no immediate reaction from Beijing.

In a statement carried by state media earlier in the day, China's Taiwan Affairs Office repeated it would not get involved in the election, saying only that it was "paying attention to across the Taiwan Strait".

A 16-year-old Taiwan singer with a South Korean girl band inadvertently shot to the top of the election agenda on polling day after she publicly apologised for holding a Taiwan flag, prompting China and Taiwan to trade accusations.

The election comes at a tricky time for Taiwan's export-dependent economy, which slipped into recession in the third quarter last year. China is also Taiwan's top trading partner and Taiwan's favourite investment destination.

Support for the DPP has swelled since 2014, when hundreds of students occupied Taiwan's parliament for weeks in the largest display of anti-China sentiment the island had seen in years.

Tsai has the tide of history against her. Ma and his predecessors all failed to bring about a lasting reconciliation with China, which considers Taiwan a rogue province to be taken by force if necessary.

Shots were traded between the two sides as recently as the mid-1970s.

At stake are relations with an ascendant and increasingly assertive China under President Xi Jinping.

- Reuters