Breast cancer survivors with obesity are at a high risk of cancer recurrence, comorbidity, and mortality. This review aims to systematically evaluate the effects of combined aerobic and resistance training (CART) on body composition, lipid homeostasis, inflammation, adipokines, cancer-related fatigue, sleep, and quality of life in breast cancer patients and survivors with overweight/obesity. An electronic search was conducted in PubMed, Web of Science, Scopus, Science Direct, Cochrane, and Google Scholar databases from inception up to January 8, 2024. Randomized controlled trials (RCTs) meeting the inclusion criteria were selected for the analysis. The Cochrane risk of bias tool was used to assess eligible studies, and the GRADE method to evaluate the quality of evidence. A random-effects model was used, and data were analyzed using mean (MD) and standardized mean differences (SMD) for continuous variables with 95% confidence intervals (CI). We assessed the data for risk of bias, heterogeneity, sensitivity, reporting bias, and quality of evidence. A total of 17 randomized controlled trials were included in the systematic review involving 1,148 female patients and survivors (mean age: 54.0 ± 3.4 years). The primary outcomes showed significant improvements in body mass index (SMD -0.57 kg/m2, p = 0.04), body fat (SMD -0.50%, p = 0.02), fat mass (SMD -0.63 kg, p = 0.04), hip circumference (MD -3.14 cm, p = 0.02), and fat-free mass (SMD 1.03 kg, p < 0.001). The secondary outcomes indicated significant increases in high-density lipoprotein cholesterol (MD -0.05 mmol/L, p = 0.008), natural killer cells (SMD 0.42%, p = 0.04), reductions in triglycerides (MD -81.90 mg/dL, p < 0.01), total cholesterol (SMD -0.95 mmol/L, p < 0.01), tumor necrosis factor α (SMD -0.89 pg/mL, p = 0.03), and leptin (SMD -0.63 ng/mL, p = 0.03). Also, beneficial alterations were found in cancer-related fatigue (SMD -0.98, p = 0.03), sleep (SMD -1.17, p < 0.001), and quality of life (SMD 2.94, p = 0.02) scores. There was very low to low confidence in the estimated effect of most of the outcomes. The present findings reveal that CART could be considered an adjunct therapy in supporting the conventional clinical approach observed following exercise. However, further high-quality research is needed to evaluate whether CART would be a valuable intervention to lower aggressive pharmacologic use in breast cancer patients with overweight/obesity.