Breast cancer prevalence has increased globally, with 12.2% of breast cancer cases identified in China. Obesity and unhealthy lifestyles are major risk factors for breast cancer. We conducted a randomized control trial to assess the feasibility and evaluate the preliminary effect of the Smartphone-Based Cancer and Obesity Prevention Education (SCOPE) program among adult biological women with a waist circumference greater than 80 cm. The SCOPE program includes tailored and culturally appropriate educational information for obesity and breast cancer prevention delivered by the research team via WeChat. The control group received non-tailored general health information via WeChat. A total of 102 women (52 intervention, 50 control) participated, and 87 (85%) completed 6-month follow-up assessments. For the primary study outcome at 6 months, women using SCOPE significantly reduced waist circumference (Cohen’sd= −0.39,p< 0.001). For secondary outcomes at 6 months, women using SCOPE significantly reduced BMI (d = −0.18,p= 0.001) and increased breast cancer-related knowledge (d = 0.48,p= 0.001) and attitude (d = 1.39,p< 0.01). No significant findings were found regarding diet self-efficacy, physical self-efficacy, or breast cancer screening barriers. The results suggest the intervention has great potential to promote the health and wellness of women.