BACKGROUND: Globally, suicide is more prevalent in older adults compared with any other age group. Although some research has identified risk and protective factors for suicidal behaviour in older adults, further research is needed to provide an up-to-date overview to inform service delivery. AIMS: This study protocol describes mixed-methods research that will examine and identify factors associated with self-harm and suicide in older adults (aged 60 years and older) living in Ireland. METHOD: Four stages will be conducted. First, data from the National Self-Harm Registry of Ireland (NSHRI), will be used to examine recent hospital self-harm presentations of older adults, including during the COVID-19 pandemic. Second, a case-series study will examine the adverse life events and psychosocial factors experienced by older adults before dying by suicide, using data from closed coronial files, through the Irish Probable Suicide Deaths Study (IPSDS). Third, risk of suicide following hospital-presenting self-harm will be examined among older adults via data linkage of the NSHRI and IPSDS. Finally, using semi-structured interviews, the service needs of older adults with suicidal behaviour will be explored from the perspectives of older adults, carers and healthcare practitioners. CONCLUSIONS: A comprehensive understanding of adverse events and psychosocial factors associated with the suicidal behaviour of older adults is needed to inform service provision. This proposed research is aligned with (inter)national priorities, mental health promotion and suicide reduction policies. It aims to address gaps in mental healthcare interventions for older adults at risk of suicide.