This study aimed to evaluate the implementation of the Brazilian Breastfeeding Network and its impact on breastfeeding indicators. Implementation was analyzed according to type, including 56 primary healthcare units from three Brazilian municipalities. For evaluation of the degree of implementation, a score was created for each unit based on compliance with Ministry of Health certification criteria. Effects of implementation were analyzed according to exclusive and overall breastfeeding rates. Eighteen (32.1%) of the units met the four criteria for certification. The study sample included 1,052 children less than one year of age, of whom 563 were less than six months old. Units that met the four criteria for certification showed higher rates of exclusive breastfeeding (44%) when compared to the other units. Difficulties in implementing the Brazilian Breastfeeding Network were identified, and breastfeeding indicators varied according to the number of certification criteria met by the primary healthcare unit.