Objective: To describe the process of best practices implementation for breastfeeding assistance for preterm and low birth weight infants. Method: Participatory research that used the evidence implementation methodology of the JBI, held at a university hospital in southeastern Brazil, with the participation of a multidisciplinary team and managers. Stages: Situational diagnosis, baseline audit and feedback, protocol development, training, implementation, and monitoring. Results: Seven audit criteria were defined. In the baseline audit, three criteria were met, with eleven barriers to be resolved being listed. The strategies carried out were protocol development and multidisciplinary and intersectoral training. After the training, compliance was achieved with the seven criteria audited in the first follow-up audit and five in the second, emphasizing the increase in compliance after the implementation of the outlined strategies. Conclusion: The project achieved the objective of improving evidence-based practice, and allowed the implementation of the institution's first breastfeeding protocol. However, it shows the need to maintain training for adherence and enculturation of new practices.