President Tayyip Erdogan stunned European allies with an overnight announcement that Turkey was withdrawing from the convention which it had been the first nation to sign.
The European treaty is known as the Istanbul Covention having been drafted in the Turkish city in 2011.
Demonstrator Selin Asarlar Celik said the women were protesting to get their freedom and rights back, and that they would not give up.
World Health Organization data shows 38% of women in Turkey are subject to violence from a partner in their lifetime, compared to 25% in Europe.
Femicide rates, for which there are no official figures, roughly tripled in Turkey over the last 10 years according to a monitoring group.