While the advent of the Internet and digital social networks has opened opportunities for global connectivity, participation, and broadcasting to agents outside the media, corporations and the state, inequities structuring societies and transnational relations still organize the flows of power in digital environments. Media scholars who resist trends of technological determinism, have argued that, in the context of social movements, mediated activism is first propelled by the politics and positionalities of activists and second by the structural features of the media platforms they employ. Political praxis, then, informs the uses of media, guiding activists' narratives and strategies in mediated spaces. This dissertation examines such intersections of media and politics by conducting a case study about the Argentine feminist collective Ni Una Menos. The study shows that Ni Una Menos employed digital media discourses to focus activism on the single yet multifaceted issue of violencia machista whose many manifestations -- from femicide to gender discrimination in the workplace -- called for the articulation of transversal coalitions. The application of such politics to mediated activism, however, posed its own challenges. The findings suggest that inequities structuring power differentials among members of different chapters of the collective -- i.e., class and professional status -- shaped their mediated practices in a way that ensured the political and symbolic dominance of the Buenos Aires chapter of Ni Una Menos. The hypervisibility of NUM Buenos Aires nationally and internationally, despite contributing to global efforts against violencia machista, has also the potential to further marginalize the struggles of women outside the capitol who dwell more vulnerable nodes of intersectional oppression. These complicated entanglements call for critical examinations of the conditions under which mediated activism and transversal politics render emancipatory outcomes for some while undermining others. The case of Ni Una Menos offers an opportunity to engage in such reflections.