Eight phenolic compounds were isolated from Eugenia pyriformis leaves fraction by semipreparative HPLC and characterized by Nuclear Magnetic Resonance (NMR) and mass spectrometry (ESI-MS). Five compounds were isolated and identified for the first time in E. pyriformis species, while this is the first report of the accumulation of isoquercitrin, quercitrin, and the aglycone quercetin in its leaves. E. pyriformis leaves and fruits extracts, as well as the compounds isolated from the leaves most active fraction, were evaluated for their antiglycation and antioxidant activities. The mixture of myricetin-3-O-(2″-O-galloyl)-α-L-rhamnoside and myricetin-3-O-(4″-O-galloyl)-α-L-rhamnoside showed the highest antiglycation activity. These results suggest that this species is a promising source of bioactive compounds. Further studies to investigate the inhibition of the glycation process in vivo are necessary to evaluate its use in the treatment and/or prevention of advanced glycation end-products (AGEs)-associated diseases.