Supporters rallied in front of the Presidential Office Building on Saturday afternoon for a music festival, where scores of Chinese celebrities pledged their support to marriage equality.
An audience of about 150,000 turned out to support a series of bills currently in parliament, offering same-sex couples the same rights as any other, including the right to adopt.
Crowds donned yellow flowers, holding signs and waved rainbow coloured flags in their support of the bill.
The concert and rally was organised after a series of protests against the bills last week, by protesters arguing that the potential law change is contrary to traditional family values.
If the law change occurred, it would make Taiwan the only country in Asia to permit gay marriage.
In contrast, in 2014 Singapore's Supreme Court upheld a law mandating a two-year jail term for men engaging in acts of "gross indecency" - meaning gay sex.