α-Glucosidase inhibitory (AGI) activity of leaf extracts from twelve pepper (Capsicum spp.) accessions was investigated to evaluate their potential as functional plant-based resources. Twelve pepper accessions were cultivated under the same conditions, and leaves were harvested six weeks after transplantation. Leaf extracts were prepared using 70% ethanol, and AGI activity was measured using p-nitrophenyl-α-D-glucopyranoside (pNPG) as a substrate by monitoring absorbance at 405 nm. Significant variation in AGI activity was observed among the tested accessions. ‘MB019’ exhibited the highest inhibitory activity (26.13%), whereas ‘MB060’ showed the lowest activity (12.24%). The control accessions, ‘MB064’ and ‘MB065’, demonstrated relatively higher inhibition rates of 56.60% and 60.31%, respectively, consistent with previous reports. These results suggest that pepper leaves contain bioactive components associated with AGI and provide a basis for the development of plant-based functional materials.