<p>Childhood trauma can have a profound impact on mental health outcomes, including suicidal ideation, particularly among older adults. This study investigates the relationship between childhood trauma and suicidal ideation in Korean older adults, focusing on the mediating effect of post-traumatic growth and the moderated mediation effect of social support. A total of 200 Korean older adults (100 men and 100 women; <i>M</i> age = 68.14 years) who reported experiences of childhood trauma participated in the study. Participants were evenly distributed by gender, and the majority had completed at least a college education. Women reported higher levels of childhood trauma compared to men. Data were collected using self-report questionnaires assessing childhood trauma, post-traumatic growth, social support, and suicidal ideation. The moderated mediation model was analyzed using Hayes’ PROCESS Macro Model 14. The results revealed that post-traumatic growth significantly mediated the relationship between childhood trauma and suicidal ideation. Notably, this indirect effect was moderated by perceived social support: it was stronger when social support was limited and became non-significant under high levels of support. These findings suggest that while post-traumatic growth can buffer the negative impact of childhood trauma, strong social support may independently mitigate suicidal ideation. These findings highlight the critical role of enhancing post-traumatic growth, particularly for those with limited social resources, while emphasizing the protective function of social support in mitigating the psychological effects of childhood trauma. Mental health interventions targeting both post-traumatic growth and social support may offer more effective strategies for reducing suicidal ideation among older Korean adults with a history of childhood trauma.</p>