Lai Ching-te, also known as William Lai, was born on 6 October 1958 in Wanli, Taipei County (now New Taipei City), to a working-class coal mining family.

Lai Ching-te's father died on 8 January 1960 of carbon monoxide poisoning while laboring in the coal mines of Wanli.

Lai married Wu Mei-ju in 1986. Wu worked for Taipower, and was based in Tainan until Lai was elected mayor of the city, and she transferred to Kaohsiung. The couple raised two sons.

Lai Ching-te won a seat representing Tainan City in the 1996 Legislative Yuan election. He was re-elected four consecutive times and served as a legislator for a total of 11 years.

Lai Ching-te obtained a Master's degree from Harvard University in 2003, specializing in rehabilitation and public health.

Lai Ching-te won the election for Mayor of Tainan in 2010 and served for seven years, winning reelection in 2014.

In September 2017, Lai Ching-te was announced as the next head of the Executive Yuan by President Tsai Ing-wen. This appointment followed Premier Lin Chuan's resignation, and Lai took office on 8 September as the 49th Premier of Taiwan.

On 26 September, Lai Ching-te made his first appearance as premier at the Legislative Yuan and expressed his views on Taiwan independence, stating that Taiwan is already an independent sovereign nation called the Republic of China and does not need a separate declaration of independence.

On 24 November 2018, Lai Ching-te announced his intention to resign from the premiership after the Democratic Progressive Party suffered a major defeat in local elections. He left office on 14 January 2019.

On 18 March 2019, Lai Ching-te registered to run in the Democratic Progressive Party presidential primary, marking the first serious primary challenge against a sitting president in Taiwanese history.

After the assassination of former Japanese prime minister Shinzo Abe, Lai made a private trip to Tokyo to pay his respects and became Taiwan's most senior official to visit Japan in five decades.

In November 2022, Lai led representatives of Taiwan's travel agencies and industry associations to Palau to foster collaborations between the two countries.

On 21 November 2023, Lai formally registered his campaign at the Central Election Commission along with his running mate, Hsiao Bi-khim.

On 13 January 2024, Lai was elected president of Taiwan with more than 40% of the vote, and will be inaugurated on 20 May 2024.

Lai Ching-te, also known as William Lai, is set to be inaugurated as the president of Taiwan on 20 May 2024. He will be the third incumbent vice president of Taiwan to become president, and the first to assume the office through election instead of a predecessor's death.