Pinanga arinasae has traditionally been used in ceremonial practices in Bali, Indonesia, yet its pharmacological properties remain unexplored. This study investigates the antioxidant and antidiabetic potential of fruit peel and seed extracts. The methanolic seed extract (PS MeOH) exhibited the highest TPC (27.87 mg GAE/g) and TFC (230.73 mg QE/g), correlating with superior antioxidant activity (ABTS IC50 = 1.25 ± 0.014 µg/mL; FRAP = 1570.54 ± 111.24 µmol TE/g) and α-glucosidase inhibition (IC50 = 7.55 ± 0.09 µg/mL). The peel methanol extract (PP MeOH) showed notable DPPH scavenging activity (IC50 = 4.64 ± 0.11 µg/mL). Enzyme kinetics revealed mixed-type inhibition for all extracts. LC-HRMS analysis showed that P. arinasae contain flavonoids, phenolics, tannin, triterpenoids, alkaloids, and organic acids. Molecular docking identified Procyanidin B2 is the most potent α-glucosidase inhibitor with docking score of −146.106 kcal/mol. These findings highlight P. arinasae extract as a promising source for antioxidant and antidiabetic agents. © 2026 Informa UK Limited, trading as Taylor & Francis Group.