<p>Physician-assisted suicide (PAS) remains a complex subject, particularly as populations age and concerns about end-of-life care intensify. Drawing on the Interpersonal Theory of Suicide, we examined how perceived burdensomeness and thwarted belongingness influence suicidal ideation and, in turn, how suicidal ideation and acquired capability affect PAS attitudes in Korean older adults. Data from 200 participants aged 65 and above were collected via an online survey measuring these constructs. Regression analyses indicated that perceived burdensomeness and thwarted belongingness each predicted suicidal ideation, with their interaction revealing that higher thwarted belongingness strengthened burdensomeness’s effect on ideation. Additionally, suicidal ideation was marginally linked to pro-PAS attitudes but became significant when acquired capability was high. A moderated mediation analysis showed that perceived burdensomeness indirectly affected PAS attitudes through suicidal ideation, conditional on thwarted belongingness and acquired capability. These findings emphasize the need for psychological assessments encompassing interpersonal risk factors, particularly among older adults contemplating end-of-life options. Integrating such considerations into clinical and policy settings may better safeguard informed decision-making and address the mental health dimensions underlying PAS.</p>