MATRIMONIO - In 2017, the island's constitutional court ruled that same-sex couples had the right to legally marry.
Parliament was given a two-year deadline and was required to pass the changes by 24 May.
Lawmakers debated three different bills to legalise same-sex unions - the most progressive of which was passed.
The two other bills, submitted by conservative lawmakers, refer to partnerships as "same-sex family relationships" or "same-sex unions" rather than "marriages".
Hundreds of gay rights supporters gathered outside the building in the capital of Taipei to await the landmark ruling.
The change comes despite public backlash to the 2017 court ruling, which pressured the government into holding a referendum.
The referendum results showed that a majority of voters in Taiwan rejected legalising same-sex marriage, saying that the definition of marriage was the union of a man and woman.