Peumus boldus is an endemic Chilean tree whose edible fruit lack a history of scientific research. The aim of this study was to determine its nutritional composition (moisture, ash, crude fiber, proteins, carbohydrates and lipids) and polyphenolic content (total phenolic content, HPLC-DAD, HPLC-MS/MS analysis) at different stages of development. The results show that the fruit decreased in ash, crude fiber and total phenolic content throughout its development, while its carbohydrate and protein content increased. An increase in phenolic molecules such as catechin and epicatechin was also observed. This is the first report on the nutritional composition and phenolic content of Peumus boldus Mol. fruits.