Nutrition plays a crucial role during pregnancy and lactation, influencing maternal and infant health, as well as human milk (HM) composition. The Mediterranean diet (MED) is recognized worldwide as a well-established healthy dietary pattern. This narrative review aims to integrate and summarize observational and interventional studies investigating the association between the MED and outcomes across the mother-milk-infant triad. A literature search was conducted in the Cochrane, Google Scholar, and PubMed databases, and 22 studies that met the eligibility criteria were included into review. The included studies were categorized into maternal outcomes ( = 13), HM composition outcomes ( = 9), and infant outcomes ( = 3). This narrative review suggests that adherence to the MED may be associated with maternal psychological health and well-being, postpartum weight loss, glucose metabolism, and the fatty acid profile of HM. Moreover, the included studies exhibited notable methodological differences that hindered direct comparisons and limited the generalizability of the findings. Future research should adopt an integrated and standardized methodology for assessing MED adherence, HM collection, and infant outcomes, considering the mother-human milk-infant triad.