Improving understanding of risk factors for risky sexual behaviour is fundamental to achieve better population sexual health. Exposure to adverse childhood experiences (ACEs) can increase the risk of poor sexual health outcomes, but most research is US-based. This study explored associations between ACEs and poor sexual health outcomes in the UK. Data from four cross-sectional ACE surveys with adult general populations in different regions of the UK from 2013-2015 ( n = 12,788) were analysed. Data included participants' demographics, ACE exposure, and four sexual health outcomes: having early sex (<16 years), having an accidental teenage pregnancy, becoming a teenage parent, or having a lifetime diagnosis of a sexually transmitted infection. ACE count was a consistent and significant predictor of all four sexual health outcomes for both males and females, with odds of these outcomes between three and seven times higher for those with 4+ ACEs compared to those with no ACEs. Increased risks of some, but not all, sexual health outcomes were also found with higher residential deprivation, younger age, being of white ethnicity, and being born to a teenage mother. Findings highlight the need for effective interventions to prevent and ameliorate the lifelong effects of ACEs. Trauma-informed relationships and sex education, sexual health services, and antenatal/postnatal services, particularly for teenagers and young parents, could provide opportunities to prevent ACEs and support those affected. Ensuring that those living in deprived areas have access to services and that barriers to uptake are addressed is also key.