This collectively authored article argues for a regional turn in the historical study of transnational activism. By considering not only pan-regional movements but also examples of borderland contexts, transregional connections and diasporic understandings of ‘region’, our discussion challenges the assumptions of universalistic perspectives on the evolution and functioning of transnational activism. Based on a Royal Historical Society-funded workshop held at and supported by Northumbria University (March 2023), the article brings together insights from diverse locations and arenas of contestation. The first part considers literatures on three macro-regional settings – South Asia, Western Europe and Latin America – to illustrate the importance of distinctive regional contexts and constructs in shaping transnational activism and its goals. The second part turns to case studies of transnational activism in and beyond Eastern Europe, West Africa, the Caribbean and East Asia. In doing so, it explores very different notions of the regional to identify how transnational activism has both shaped and been shaped by these ideas. Taken together, the two parts highlight the role of regional identities and projects in challenging inequalities and external domination. Our analysis and examples indicate the possibilities of a regionally rooted approach for writing histories of transnational activism.