Background; Breast cancer is a significant public health issue in sub-Saharan Africa and the second commonest cancer overall. In Ethiopia, most women present at the late-stage presentation. This is because Ethiopian government gives less attention, and is not well-studied as well. Therefore, it is important to assess delays in diagnosis and treating breast cancer that has been associated with a more advanced stage of the disease and a decrease in patient survival rates.Objective: To assess the magnitude and associated factors for late diagnosis of breast cancer among women attending Hawassa University Comprehensive Specialized Hospital in Southern Ethiopia. Methodology: A facility-based cross-sectional study was conducted from December to January 2019. Data were collected from 261 consecutively selected clients based on the arrival of their hospital visit by using a pretested structured questionnaire and checklist. Physicians performed physical examinations and diagnoses. Data was checked for completeness and consistency, and entered into epi data, then exported to SPSS for analysis. Descriptive, Bivariate, and multivariable logistic regression analyses were performed using SPSS Version 25 Statistical Software.Results: The magnitude of late diagnosis of breast cancer was 86.3%. The woman who had no initial advice for breast biopsy [AOR=5.1, 95% (CI=1.4-18.9)], not sharing the problem to others [AOR=4.7, 95% (CI=1.8-12.2)] and using traditional and faith healers as a first treatment choice [AOR=3.3, 95% (CI=1.2 - 8.8)] were associated with late diagnosis of breast cancer.Conclusions: The majority of women having breast cancer were diagnosed at a late stage. It needs attention to provide better options of the modern health service, and providing accessible initial advice for breast biopsy, and creating awareness about the benefit of sharing problems with family to improve the health of mothers by early diagnosing and managing the breast cancer.