Unsafe sanitation practices can severely affect public health. Strengthening psychological ownership, the feeling of owning an object (e.g. the latrine) individually or collectively, may promote safe sanitation practices, e.g. decreased open defecation. This study investigated psychological ownership in communities that participated in a sanitation intervention. We used follow-up survey data of a cluster-randomised controlled trial in rural Ghana (N = 2012 households), which assessed psychological ownership, and safe sanitation outcomes. The data were analysed using multilevel modelling and generalised estimating equations. In line with our assumptions, greater psychological ownership for the latrine related to decreased open defecation. Higher individual psychological ownership for the open defecation space related to safe sanitation outcomes, whereas collective ownership related to lesser safe sanitation. The present study shows that the concept of psychological ownership may play an important role in safe sanitation. Collective and individual psychological ownership seem to distinctly relate to safe sanitation outcomes, which has high relevance for promoting communities’ health behaviour.