Background:Breast cancer is the leading malignancy among women globally and the most prevalent cancer among women in Rwanda. Despite this, limited research exists on breast cancer prevalence and associated factors among reproductive-aged women in Rwanda. Methods:This prospective study collected quantitative data from 288 women aged 15 49 years who were initially screened positive for breast cancer at health facilities and transferred to Butaro Cancer Referral Hospital for confirmatory testing. Data were analyzed using Statistical package for data science (SPSS) version 21, with logistic regression applied to determine associations between breast cancer and socio demographic, reproductive, and behavioral factors.Results:The study found a high prevalence of breast cancer among the sample population, with 76.7% testing positive. Age, alcohol consumption, and lack of physical exercise were significantly associated with breast cancer risk. Women aged 35-39 were 4.7 times more likely to have breast cancer than those under 30 (AOR = 4.7, 95% CI:1.99 - 11.38, p < 0.001). Women consuming modern alcohol had a 14.2-fold higher risk (AOR = 14.2, 95% CI: 3.39 - 59.57, p < 0.001), while those engaging in physical activity had lower odds (AOR = 0.1, 95% CI: 0.01 - 0.84, p = 0.033).Conclusion:A high prevalence of breast cancer was observed, call for targeted prevention strategies, including community-based awareness campaigns on the risks of alcohol consumption and promoting physical exercise, as well as strengthening early screening programs to reduce the burden of breast cancer in Rwanda.