Objective: To systematically evaluate the safety, feasibility, and effect of exercise among women with stage II+ breast cancer. Data Sources: CINAHL, Cochrane, Ebscohost, MEDLINE, Pubmed, ProQuest Health and Medical Complete, ProQuest Nursing and Allied Health Source, Science Direct and SPORTDiscus were searched for articles published before March 1, 2017. Study Selection: Randomized, controlled, exercise trials involving at least 50% of women diagnosed with stage II+ breast cancer were included. Data Extraction: Risk of bias was assessed and adverse event severity was classified using the Common Terminology Criteria. Feasibility was evaluated by computing median (range) recruitment, withdrawal, and adherence rates. Meta-analyses were performed to evaluate exercise safety and effects on health outcomes only. The influence of intervention characteristics (mode, supervision, duration and timing) on exercise outcomes were also explored. Data Synthesis: There were no differences in adverse events between exercise and usual care (risk difference: <0.01 ([95% CI: -0.01, 0.01], P=0.38). Median recruitment rate was 56% (1%-96%), withdrawal rate was 10% (0%-41%) and adherence rate was 82% (44%-99%). Safety and feasibility outcomes were similar, irrespective of exercise mode, supervision, duration, or timing. Effects of exercise for quality of life, fitness, fatigue, strength, anxiety, depression, body mass index and waist circumference compared with usual care were significant (standardized mean difference range: 0.17-0.77, P<0.05). Conclusion: The findings support the safety, feasibility, and effects of exercise for those with stage II+ breast cancer, suggesting that national and international exercise guidelines appear generalizable to women with local, regional, and distant breast cancer.