Triple-negative breast cancer (TNBC) is associated with a poor prognosis. Surgery, radiotherapy, chemotherapy, and referral for genetic counseling are the standard of care. We assessed TNBC prevalence, management, and outcome using data from the population-based Geneva cancer registry. 2591 women had a first invasive stage I-III breast cancer diagnosed between 2003 and 2011. We compared TNBC to other breast cancers (OBC) by χ -test and logistic regression. Kaplan-Meier survival curves, up to 31-12-2014, were compared using log-rank test. TNBC risk of mortality overall (OS) and for breast cancer (BCSS) was evaluated through Cox models. Linkage with the Oncogenetics and Cancer Prevention Unit (OCPU) database of the Geneva University Hospitals provided genetic counseling information. TNBC patients (n = 192, 7.4%) were younger, more often born in Africa or Central-South America than OBC, had larger and more advanced tumors. 18% of TNBC patients did not receive chemotherapy. Thirty-one (17%) TNBC women consulted the OCPU, 39% among those aged <40 years. Ten-year survival was lower in TNBC than OBC (72% vs. 82% for BCSS; P < 0.001; 80% vs. 91% for OS; P < 0.001). The mortality risks remained significant after adjustment for other prognostic variables. The strongest determinants of mortality were age, place of birth, and lymph node status. A substantial proportion of TNBC patients in Geneva did not receive optimal care. Over 60% of eligible women did not receive genetic counseling and 18% did not receive chemotherapy. To improve TNBC prognosis, comprehensive care as recommended by standard guidelines should be offered to all patients.