To evaluate the association between maternal employment and breastfeeding (both duration and status) in Mexican mothers using data from three National Health and Nutrition Surveys conducted in 1999, 2006 and 2012. We analyzed data from the 1999 National Nutrition Survey, the 2006 National Nutrition and Health Survey, and the 2012 National Nutrition and Health Survey (NNS-1999, NHNS-2006 and NHNS-2012) on 5,385 mothers aged 12-49 years, with infants under 1 year. Multivariate logistic regression models were used to analyze the association between breastfeeding and maternal employment adjusted for maternal and infant's socio-demographic covariates. Maternal formal employment was negatively associated with breastfeeding in Mexican mothers with infants under 1 year. Formally employed mothers were 20 % less likely to breastfeed compared to non-formally employed mothers and 27 % less likely to breastfeed compared to unemployed mothers. Difference in median duration of breastfeeding between formally employed and unemployed mothers was 5.7 months for NNS-1999, 4.7 months for NNHS-2006 and 6.7 months for NNHS-2012 respectively (p < 0.05). In NHNS-2006 and NHNS-2012, health care access was associated with longer breastfeeding duration. Maternal employment has been negatively associated with breastfeeding in Mexican mothers of <1 year infants at least for the last 15 years. For Mexicans involved in policy design, implementation or modification, these data might offer robust evidence on this negative association, and can be used confidently as basis for conceiving a more just legislation for working lactating women.