Garri is a popular, easy to prepare, storable and low cost staple food made from cassava roots, but lacks the right balance of nutrients. The aim of this study was to evaluate the effect of incorporating mango fruit mesocarp flour as a supplement on the functional, physicochemical and sensory properties of garri. Four blend ratios and codes of 100:0 (C100M0G), 90:10 (C90M10G), 80:20 (C80M20G) and 70:30 (C70M30G) were developed for cassava mash and mango fruit mesocarp flour respectively. The proximate composition, vitamin and elemental composition, functional properties and sensory attributes of the samples were analysed using standard methods. Results from this study revealed that increase in mango fruit mesocarp flour supplementation in the garri increased the protein (1.01 to 1.42%), fat (negligible increase), ash (0.47 to 1.28%), carbohydrate (82.99 to 87.15%), Vitamin A (3.00 to 160.66 µg/100g), Vitamin C (10.23 to 33.34 mg/100g), calcium (0.43 to 1.04%), potassium (0.07 to 0.28%), sodium (0.05 to 0.22%) contents as well as sensory attributes whose values ranged from 5.7 to 7.9 on a 9 point hedonic scale; while decreasing the moisture (12.60 to 7.85%) and crude fibre (2.93 to 2.30%) contents in addition to the bulk density (0.66 to 0.51 g/ml), water absorption capacity (2.11 to 1.30 g/g) and swelling capacity (1.09 to 0.78 g/g). Therefore, adding mango fruit mesocarp flour as supplement has the ability to enhance the macro- and micro-nutrient content, functional properties and sensory characteristics of garri. Sensory evaluation revealed that C70M30G was the most preferred blend formulation.