In the past 20 years, feminist non-governmental organizations (NGOs) have increasingly engaged in transnational legal activism in the Americas not only to seek individual remedies for victims/survivors of abuses of women’s human rights, but also to pressure states to make legal and policy changes, to promote human rights cultures and to strengthen the demands of women’s movements. Yet the scholarship on transnational feminist activism overlooks transnational litigation practices. Studies of transnational legal mobilization tend to ignore the relationship between human rights and feminist advocacy networks, or between NGOs and the victims whose knowledge and experience serve as the basis for transnational litigation practices. This article draws from research on transnational legal activism over cases of women’s human rights presented to the Inter-American Commission on Human Rights against Brazil. It builds on the ‘epistemologies of the South’ framework to examine how human rights NGOs that specialize in transnational litigation, feminist advocacy NGOs, grassroots feminist organizations and victims/survivors (or family victims) of intimate (partner) violence against women engage in transnational legal activism, negotiate power relations, and exchange their knowledges/visions on human rights and justice. The legalistic view on human rights held by the more professionalized NGOs tends to prevail over grassroots feminist organizations’ and survivors’ perspectives on human rights and justice. To promote global justice, human rights activism must include epistemic justice and must legitimate all types of knowledge produced by all the actors involved.