Idli is a traditional fermented South Indian food prepared primarily from rice and black gram and is widely consumed because of its soft texture, digestibility and nutritional acceptability. The present study was undertaken to develop a functional idli by incorporating selected natural prebiotic ingredients and to evaluate the resulting products for nutritional, sensory and physicochemical characteristics. Natural prebiotic ingredients such as banana flour, oats, inulin-rich ingredients and dietary-fibre-rich plant materials were incorporated into the conventional idli formulation at different levels. A control formulation without prebiotic supplementation and four fortified formulations were prepared. The products were evaluated for proximate composition, dietary fibre, selected physicochemical properties and sensory acceptability using a structured hedonic scale. The experimental formulations demonstrated an increase in dietary fibre and ash content compared with the control, while moderate incorporation of prebiotic ingredients maintained acceptable moisture, pH, texture and sensory characteristics. Among the developed products, the formulation containing a moderate level of prebiotic ingredients showed the highest overall acceptability. The findings suggest that incorporation of natural prebiotic ingredients into idli can be a promising approach for developing a traditional cereal-legume food with enhanced functional and nutritional properties.