Based on a qualitative study conducted in the township of Chibavi in Mzuzu City, Malawi, this paper seeks to contribute to the emerging debate as to why orphans may be more vulnerable to the AIDS epidemic through the lens of an informal labour relation locally known as ganyu. The paper argues that although ganyu has deep roots in the country's history and has served as an escape from extreme poverty in rural areas, its transition to the urban landscape is associated with an emergent practice of sexual exchange between those who seek ganyu and those who recruit the workers. While youth in Chibavi generally work ganyu, the particularly oversized domestic roles of encumbered orphans against a backdrop of extremely deprived material circumstances and weak kin ties propelled them into prolonged ganyu contracts and compelled them to more readily concede to sexual demands ‘imposed’ by those who offered them ganyu. Drawing on geographic perspectives from political ecology of health and tracing the historical and geographic interconnections of ganyu, this study adds to the understanding of how the spatial transformation of this enduring ad hoc labour makes it a relation that potentially shapes vulnerability to HIV in Malawi. This study also wrestles with the question of why current policy debates do not reflect these realities in a country with one of worst AIDS epidemics, and in turn, makes relevant policy recommendations.