Objective: Adjustment to retirement is heterogeneous in nature, and for some, but not all individuals, may require well-being support. However, limited information is available on the types of psychosocial interventions that can be effective during this time of transition with pre-retirees or retirees. This review identified psychosocial interventions with adults before and during retirement, and their effectiveness in maintaining or increasing well-being. Method: Following PRISMA guidelines, a multi-database systematic literature review, with a two-stage screening process, was conducted utilising narrative synthesis. Records were independently screened by two screeners against set inclusion and exclusion criteria. Results: Two thousand four hundred and thirty-six records were identified for screening with 20 studies found eligible for final review. These included seven randomised controlled trial studies (RCT), six non-randomised quasi-experimental controlled studies, and seven single group pre/post intervention studies. Interventions covered cognitive behavioural therapy (CBT), positive psychology, mentoring, family therapy and others. Conclusions: The review highlighted the benefits of psychosocial support to adults' well-being before and after they retire, especially with participation in group-based programs utilising elements of CBT. There was also evidence for well-being maintenance with longer running interventions. Results should be considered in the development of future psychosocial interventions to support individuals during this important life phase in older adulthood.