Aim: Exercise for prostate cancer (PC) survivors has been shown to be effective in addressing metabolic function and associated comorbidities (e.g. diabetes, cardiovascular disease, etc.), as well as sarcopenia and significant functional impairment resulting from long term androgen deprivation. The aim of this study is to determine the cost effectiveness of a supervised exercise intervention for long term PC survivors who received radiation therapy and androgen deprivation therapy. Method: We conducted a cost effectiveness analysis of a multi-centre randomised controlled trial (RCT) of supervised exercise training (resistance and aerobic) in long-term PC survivors (>5 years post diagnosis) alongside the Trans-Tasman Radiation Oncology Group (TROG) 03.04 Randomised Androgen Deprivation and Radiotherapy (RADAR) trial. Results: In comparison to usual care, the total cost of the intervention was $546 from a health care payer perspective. The incremental cost per QALY gain was $65,050 (2018 AUD). Conclusions: This is the first cost effectiveness analysis of a supervised exercise intervention for long term PC survivors after curative radiotherapy and adjuvant ADT. The results indicate the intervention is effective, but not cost effective at a generally accepted WTP of $50,000. Evidence to support cost savings from post intervention outcomes would potentially reveal greater benefits such as reduced health service utilisation, chronic disease, falls and fractures and contribute to a more comprehensive analysis and more favourable cost effectiveness outcome. Future research should address these deficits via a larger trial with longer follow up.