She has become the highest-ranking American official to visit the self-ruled island claimed by China in 25 years.
Her visit has been closely watched by mainland China, and by scores of people who used the website Flightradar24 to track the aircraft she was on as it made its way to Taiwan.
Ms Pelosi and her delegation disembarked from a US Air Force transport plane at Songshan Airport in downtown Taipei late on Tuesday and were greeted by Taiwan’s foreign minister, Joseph Wu, and Sandra Oudkirk, the top US representative in Taiwan.
She is expected to meet Taiwan’s president, Tsai Ing-wen, and parliament tomorrow and fly out of the island in the afternoon.
Beijing has warned the visit would undermine China-US relations, and the foreign ministry said it seriously violated China’s sovereignty and territorial integrity.
In a statement issued just after her arrival in Taipei late on Tuesday, China’s foreign ministry said it had lodged a strong protest with the US.
State media announced military exercises later this week, and Chinese war planes flew over the Taiwan Strait before her arrival.
Ms Pelosi is on a tour of Asia that includes announced visits to Singapore, Malaysia, South Korea, and Japan. Her stop in Taiwan had not been announced, but had been widely anticipated.
China claims self-governed Taiwan as its own, and a foreign ministry spokesman said earlier this week that any visit by Ms Pelosi would be “a gross interference in China’s internal affairs”.
“The Chinese People’s Liberation Army will never sit idly by,” they warned.
Ms Pelosi’s visit caps a long history of the politician confronting Beijing.
More than 30 years ago, she was a junior senator when she sneaked away from an official delegation and angered China’s government by showing up in Tiananmen Square and unfurling a banner honouring the dissidents killed in the 1989 protests.