This special issue investigates a form of urban practice – termed ‘socio-technical practice’ – that utilizes technical knowledge, particularly in architecture, planning and related spatial disciplines, as a means of ‘allyship’. This practice operates within partnerships and coalitions aimed at supporting urban residents, grassroots organizations and social movements advocating for fairer cities. By allyship, we refer to a committed and accountable positioning by practitioners who intentionally leverage their skills, resources and institutional access to support and amplify the struggles of those who have been structurally marginalized, without co-opting or leading them. The collection critically examines how diverse forms of socio-technical practice are being redefined and understood in urban contexts increasingly affected by inequality, climate disruption and displacement. While we acknowledge that the term ‘socio-technical practice’ applies to actions taken by those operating beyond the professional sphere, this special issue will specifically focus on those who engage from this practitioner position.