The posters in the heavily police-monitored demonstration display slogans such as "Women's murder is political", and "Protect women, not the perpetrators".
- We do not give up.
We will stay here until we get our freedom and our convention back, says student Selin Asarlar Celik.
President Recep Tayyip Erdogan surprised the outside world with the news last week.
According to Erdogan's conservative Islamist AK Party, the convention undermines family structures and encourages violence, but women have expressed strong concern that the decision to leave it jeopardizes their security.
The Istanbul Convention is a comprehensive agreement aimed at preventing and combating violence against women and girls, as well as domestic violence. The convention was presented in 2011 and entered into force in 2014.