The parliament voted 110-30 to back the Istanbul Convention, which also has caused divisions within the ruling conservative Croatian Democratic Union party.
Opponents in the staunchly Catholic country have argued that the treaty indirectly legalizes gay marriage and gives rights to transgender people.
Thousands of far-right supporters protested the convention on Thursday in the Adriatic town of Split. Some of them chanted a World War II battle slogan used by Croatia's pro-Nazi regime at the time.
Also reflecting Croatia's recent shift toward right-wing sentiments, 14 parliament lawmakers from the ruling HDZ party voted against the government-backed document.
Prime Minister Andrej Plenkovic, who is the party leader, said "that is their choice."
"It is good that we have approved the convention," said Plenkovic. "We should work to reduce the divisions."
Plenkovic also insisted that the massive protest in Split against the convention "was about a different agenda," implying the conservatives want to topple his government.
Since joining the EU in 2013, Croatia has been drifting toward the right, including some who deny the Holocaust and have re-appraised the Ustasha regime that ruled the country during WWII when tens of thousands of Jews, Serbs and Roma perished in concentration camps.
Liberal convention backers separately commemorated women killed in domestic violence.
The document was adopted by the Council of Europe in 2011 in a bid to fight violence against women throughout Europe, but until Friday it had not been ratified by Croatia's parliament, when it became a law.
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