Utilisation and application of implementation science in complex suicide prevention interventions: A systematic review

•There is a growing realisation of the importance of a combination of evidence-based strategies to address suicide.•Current research on how complex interventions in suicide research are delivered in real life settings is limited.•Implementation science offers approaches to better understand how and why interventions operate.•Nineteen complex suicide prevention interventions implemented between 1990 and 2022 were identified.•The extent of utilisation of implementation science found to be inconsistent and incomprehensive.•Understanding the delivery of complex suicide prevention interventions is key in understanding what works.