Social work in prisons not only works with and for people who are confined; it also constitutes a form of social work that is carried out under conditions of confinement. This article draws on carceral geography to understand the corporeal and spatial aspects of social work in prison settings. Based on insights from two prisons in Switzerland, we argue that understanding carceral social work as a spatial and materially situated practice helps to gain deep insight into the intricate layers of meaning and powerful modes of functioning of prisons and of the people involved. In particular, it shows how the way social work is carried out in prison is supported and strongly structured by the spatiality of the prison itself, allowing for counselling, desk-type social work, rather than for social work that actively initiates and creates spaces for encounters or activities.