Current research on how energy vulnerability impacts the meaning of ‘home’, especially for those in marginalised groups, is limited. This research adds to the understanding of how high energy prices affect one of the most vulnerable sections of society: those at risk of or with experiences of homelessness. Through 15 in-person interviews with social housing tenants in Ireland who have recently exited homelessness, we find that high energy prices continue to affect the psychosocial benefits associated with ‘home’ in three different ways: 1) the constant pressure of monitoring energy expenses and lifestyle adjustments; 2) navigating the uncertainty of energy expenses and; 3) the impacts of negative emotions like stress and anxiety induced by high energy prices on tenants' fragile state of mental health and wellbeing. Based on the findings, we argue that living with high energy prices continues to interfere with the meaning of ‘home’ in an already vulnerable cohort, leading to deep senses of ontological insecurity. Therefore, specifically designed policy support is required to address energy vulnerability in people exiting homelessness, as ontological insecurity affects their mental and physical wellbeing, jeopardising their chances of a permanent transition from homelessness. Our findings indicate that perhaps a dual financial and social support system is needed to address the specific energy needs of vulnerable groups, that would provide intensive guidance for them as they settle into new routines and responsibilities. Policies to solve homelessness can be more impactful if they adequately address energy affordability-related challenges while a person transitions from homelessness.