Previous studies have shown a high level of noncompliance with recommendations on breastfeeding duration, especially in France. The objective was to describe the association between breastfeeding initiation and duration and the statutory duration of postnatal maternity leave, the gap between the end of legal maternity leave and the mother's return to work, and maternal working time during the first year post-partum. Analyses were based on 8,009 infants from the French nationwide ELFE cohort. We assessed the association with breastfeeding initiation by using logistic regression and, among breastfeeding women, with categories of breastfeeding duration by using multinomial logistic regression. Among primiparous women, both postponing return to work for at least 3 weeks after statutory postnatal maternity leave (as compared with returning to work at the end of the statutory period) and working less than full-time at 1 year post-partum (as compared with full-time) were related to higher prevalence of breastfeeding initiation. Among women giving birth to their first or second child, postponing the return to work until at least 15 weeks was related to a higher prevalence of long breastfeeding duration (at least 6 months) as compared with intermediate duration (3 to <6 months). Working part-time was also positively related to breastfeeding duration. Among women giving birth to their third child or more, working characteristics were less strongly related to breastfeeding duration. These results support extending maternity leave or working time arrangements to encourage initiation and longer duration of breastfeeding.