The advanced-stage diagnosis of breast cancer reveals the inequalities associated with socioeconomic conditions and the offer of health services. This study analyzes the prevalence of advanced breast cancer and its relationship with individual and contextual socioeconomic indicators and offer of health service. A cross-sectional study is presented herein, on the assessment of malignant breast neoplasms in women diagnosed between 2006 and 2015 (n = 195,201). Data were collected from the Hospital Cancer Registry (HCR), Atlas of Human Development in Brazil, and from the National Registry of Health Institutions (NRHI). A multilevel Poisson Regression was carried out with random intercept. The prevalence of advanced breast cancer diagnosis was 40.0%. Advanced staging was associated with younger age groups (PR 1.41), race/nonwhite (PR 1.13), lower education levels (PR 1.38), and public access to health services (PR 1.25). There was also an association with a low density of mammographic equipment (PR 1.08), and with low indices of local social inequality (PR 1.33) and human development (PR 0.80). This study maps and highlights the causes related to inequalities in the diagnosis of advanced breast cancer in Brazil, and presents essential data to reorient public policies and health-related actions to strengthen the control of breast cancer in Brazil.