Non-metastatic breast cancer patients often experience psychological distress which may influence disease progression and survival. Cognitive-behavioral stress management (CBSM) improves psychological adaptation and lowers distress during breast cancer treatment and long-term follow-ups. We examined whether breast cancer patients randomized to CBSM had improved survival and recurrence 8-15 years post-enrollment. From 1998 to 2005, women (N = 240) 2-10 weeks post-surgery for non-metastatic Stage 0-IIIb breast cancer were randomized to a 10-week, group-based CBSM intervention (n = 120) or a 1-day psychoeducational seminar control (n = 120). In 2013, 8-15 years post-study enrollment (11-year median), recurrence and survival data were collected. Cox Proportional Hazards Models and Weibull Accelerated Failure Time tests were used to assess group differences in all-cause mortality, breast cancer-specific mortality, and disease-free interval, controlling for biomedical confounders. Relative to the control, the CBSM group was found to have a reduced risk of all-cause mortality (HR = 0.21; 95 % CI [0.05, 0.93]; p = .040). Restricting analyses to women with invasive disease revealed significant effects of CBSM on breast cancer-related mortality (p = .006) and disease-free interval (p = .011). CBSM intervention delivered post-surgery may provide long-term clinical benefit for non-metastatic breast cancer patients in addition to previously established psychological benefits. Results should be interpreted with caution; however, the findings contribute to the limited evidence regarding physical benefits of psychosocial intervention post-surgery for non-metastatic breast cancer. Additional research is necessary to confirm these results and investigate potential explanatory mechanisms, including physiological pathways, health behaviors, and treatment adherence changes.