Introduction Although health system utilization and screening intensity may influence breast cancer (BC) incidence, its burden is high and the impact of occupational factors on this disease is of increasing concern. We aimed to assess the effect of some occupational factors on BC incidence and stage at diagnosis in French-speaking Switzerland. Material and Methods Swiss female residents from the Swiss National Cohort with available occupation were matched with data from four Swiss cancer registries over the period 1990-2014. We calculated BC Standardized Incidence Ratios (SIRs) by occupation and analyzed the association between occupational factors and BC incidence using negative binomial regression, and on the stage at diagnosis using multinomial logistic regression. Results The cohort comprised 381,873 women and 8,818 incident BC cases. We observed the highest SIRs in Physicists, chemists and related professionals (2.10, 95%-IC: 1.22-3.36), Legal professionals (1.87, 95%-IC: 1.42-2.48), and College, university, and higher education teaching professionals (1.61, 95%-IC: 1.07-2.33). When adjusted for age, calendar period, canton, civil status and nationality, we identified occupation, skill level, and socio-professional category as significantly associated with BC incidence. In addition, women with the lowest skill level were more likely to be diagnosed at the late stage (3-4) than those with the highest level, while we identified the opposite for women diagnosed at stage 1. Conclusions These findings call for further research on occupations with a high incidence and on the differences in stage at diagnosis by skill level.