Survivors of prostate cancer experience treatment-related physical side effects that can compromise emotional well-being for years post-treatment. There is limited research investigating how social support and the use of coping may affect the emotional well-being of this population following treatment. The aim of this study was to investigate how social support and coping impact emotional well-being 2 years after treatment in survivors of localized prostate cancer who have received either radical prostatectomy or radiotherapy. Psychosocial and disease-specific measures were administered to an ethnically and demographically diverse sample of 180 men treated for localized prostate cancer at baseline and at 2-year follow-up. Regression analyses demonstrated that higher levels of social support at baseline predicted better emotional well-being 2 years later. Furthermore, higher levels of adaptive coping at baseline partially mediated the relationship between social support and emotional well-being. Supportive relationships may contribute to improved emotional well-being following treatment by facilitating the use of adaptive coping strategies. Attention should be given to strengthening social support networks and educating survivors of prostate cancer on adaptive coping techniques.