Around the world, rental housing is frequently seen as secondary to home ownership; yet it plays a crucial role in many countries. In particular, rental housing in urban informal neighbourhoods has a critical but consistently overlooked role in housing the most vulnerable households in the global South. If better policy and practice are to be pursued, there is a need for improved data on rental housing in urban informal settlements, and in particular, better understanding of 'the lived experiences of the poor'. This article responds to these empirical gaps in debates on informality and rental housing with qualitative research on residents' experiences of informal rented housing in two Colombian cities, Bogotá and Cali. The article frames informal rental housing as an essential option for diverse low-income households for whom ownership is not accessible or attractive. In this way, it also contributes to policy and theoretical debates calling for a better understanding of the dynamics, possibilities and potential of informal housing.