Berberis microphylla G Forst (Calafate) have been used in traditional medicine from prehispanic times in Patagonia. In the last decade the consumption of the fruit has been increased due to their antioxidant capacity, and because several studies demonstrated health benefits associated with the protection against atherosclerosis and other metabolic diseases. Nevertheless, the bioactivity properties of the leaves, a by-product of agronomic management, have been poorly studied. Recently, 108 compounds mainly hydroxycinnamic acids, flavonols, and berberine were identified in a methanolic extract of the leaves, demonstrating great potential for the development of new functional beverages. Based on these, for first time a comprehensive chemical characterization and bioactivity was evaluated for a Calafate leaves infusion prepared in hot water. For this, chemical characterization of the infusion was performed by UHPLC-Q-TOF and TXRF. Bioactivity was assayed by antioxidant capacity, cell cytotoxicity, and cell oxidative stress assays. Inhibition of both Aβ aggregation for Alzheimer's disease and gastrointestinal enzymes for metabolic syndromes were evaluated. The results show that the infusion is rich in hydroxycinnamic acids and other bioactive compounds. The infusion does not contain toxic metals or cytotoxicity activity. The infusion can reduce intracellular reactive oxygen species in HUVEC cells and showed a reduction in the Aβ aggregation being a potential beverage for Alzheimer's prevention. Finally, the infusion had in-vitro hypoglycemic and hypolipidemic effects. These results support the usage of Berberis microphylla G Forst leaves as a new functional beverage.