Adverse childhood experiences (ACEs) can affect individuals' resilience to stressors and their vulnerability to mental, physical and social harms. This study explored associations between ACEs, financial coping during the cost-of-living crisis and perceived impacts on health and well-being. National cross-sectional face-to-face survey. Recruitment used a random quota sample of households stratified by health region and deprivation quintile. Households in Wales, UK. 1880 Welsh residents aged ≥18 years. Outcome variables were perceived inability to cope financially during the cost-of-living crisis; rising costs of living causing substantial distress and anxiety; and self-reported negative impact of rising costs of living on mental health, physical health, family relationships, local levels of antisocial behaviour and violence, and community support. Nine ACEs were measured retrospectively. Socioeconomic and demographic variables included low household income, economic inactivity, residential deprivation and activity limitation. The prevalence of all outcomes increased strongly with ACE count. Perceived inability to cope financially during the cost-of-living crisis increased from 14.0% with 0 ACEs to 51.5% with 4+ ACEs. Relationships with ACEs remained after controlling for socioeconomic and demographic factors. Those with 4+ ACEs (vs 0 ACEs) were over three times more likely to perceive they would be unable to cope financially and, correspondingly, almost three times more likely to report substantial distress and anxiety and over three times more likely to report negative impacts on mental health, physical health and family relationships. Socioeconomically deprived populations are recognised to be disproportionately impacted by rising costs of living. Our study identifies a history of ACEs as an additional vulnerability that can affect all socioeconomic groups. Definitions of vulnerability during crises and communications with services on who is most likely to be impacted should consider childhood adversity and history of trauma. [Abstract copyright: © Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.]