The petition gathered 50,000 signatures, the number required to have an issue debated in parliament.
It was created by the ‘Association for Real Marriage’ on the citizens’ initiative website, and gained the support by 6pm on Sunday.
The goal was reached with two-and-a-half months to spare, according to the terms of the citizens’ initiative scheme.
The President of Finland in February signed a law legalising gender-neutral marriage – but couples will face a long wait before they are allowed to marry as it will not come into force until March 2017.
In November, the Finnish Parliament passed a citizens’ initiative on gender-neutral marriage by a tight vote of 105-92, after a number of previous defeats.
The petition calls for the parliament to reverse the law.