Objective: To investigate the in vitro antioxidant activity of ethanolic extract of Artocarpus heterophyllus (A. heterophyllus) stem bark and its inhibitory effect on a-amylase and a-glucosidase. Methods: The A. heterophyllus stem bark was extracted using methanol and tested for antioxidative activity. Results: The results revealed that the ethanolic extract has polyphenolics and free radical scavenging compounds which were significantly higher (P < 0.05) than their respective standard, at concentration dependent manner. The ethanolic extract of A. heterophyllus stem bark was observed to show inhibitory activities on a-amylase and a-glucosidase with IC50 of (4.18 ± 0.01) and (3.53 ± 0.03) mg/mL, respectively. The Lineweaver-Burk plot revealed that ethanolic extract of A. heterophyllus stem bark exhibited non-competitive inhibition for a-amylase and uncompetitive inhibition for a-glucosidase activities. Also, gas chromatography–mass spectrometry showed the presence of different bioactive compounds in extract. Conclusions: Therefore, it can be inferred from this study that ethanolic extract of A. heterophyllus stem bark may be useful in the management of diabetes mellitus probably due to bioactive compounds observed in the extract.