Officially accepting the party's nomination, Tsai pledged to maintain the "status quo" with China, as her party -- traditionally sceptical of Beijing -- faces tough questions on its cross-strait policy.
Taiwan split from China in 1949 after a civil war, but Beijing still regards the island as part of its territory awaiting unification.
While ties have warmed under current president Ma Ying-jeou, fears over Beijing's increasing influence have grown, contributing to the worst-ever defeat of his ruling China-friendly Kuomintang (KMT) at local elections in November.
"The most important thing in terms of diplomacy is the handling of cross-strait relations," Tsai said to reporters at a press conference immediately after her nomination.
"The basic principle is to maintain the status quo," she said.
"After we (the DPP) come to power we will examine agreements (with China) case by case, according to the law, and will continue negotiations."
But she said that the party would also be "guided by the public's will".
There have been smaller demonstrations recently over Taiwan's application to become a member of the Asian Infrastructure Investment Bank (AIIB) and new flight routes announced by China which cross Taiwanese waters.
Tsai attacked the KMT over the island's growing wealth gap and youth unemployment, vowing to rehabilitate the slowing economy.
"The government has shut the door on the public and refused to listen to them," she said.
Tsai, 58, who is chairwoman of the DPP, had been widely expected to be named as the official candidate for the presidential elections in January 2016.
It will be her second shot at the presidency after losing to current leader Ma in 2012 by six per cent.
"The night we were beaten, there were many young people crying," an emotional Tsai said at the DPP headquarters tosday.
"Today I want to tell you all -- and myself -- I will do whatever I can to turn those tears to laughter."
Despite Taiwan's conservatism, women have long constituted a high-profile and vocal segment in parliament.
