The field of transitional justice lacks a comprehensive understanding to the role that social solidarity plays in transitional justice contexts. There is a lack of knowledge of the means through which victims can exercise their social agency to explore mechanisms of reparation beyond truth commissions, tribunals, and trials. This article argues that social solidarity is a crucial dimension and a novel perspective from which to develop transitional justice processes from a victims’ point of view in post-conflict societies. Employing a participative action research method, this article’s importance rests in the idea that Colombian victims’ groups from Eastern Antioquia view social solidarity as a crucial dimension of transitional justice in developing the project Cartography and Identification of Mass Graves. It establishes that this effort is a powerful novel mechanism to claim justice, reparation, recognition, and guarantees of non-recurrence from an unofficial angle. It demonstrates that comprehending social solidarity as a vital dimension of transitional justice stresses the importance of victims’ social agency to conduct collaborative collective actions in order to support inclusive processes of disarmament, demobilisation, and reintegration (DDR) beyond official agendas and narratives.