Abstract Thermal conductivity of bricks is an important parameter as it directly influences the heat losses from buildings and thus increases the energy consumption. The main focus of this study was to develop thermally efficient burnt clay bricks incorporating agricultural wastes on industrial scale. For this purpose, agricultural wastes (sugarcane bagasse ash (SBA) and rice husk ash (RHA)) were acquired from a sugar industry and a brick kiln. Burnt clay bricks were manufactured in an industrial kiln by incorporating SBA and RHA in various dosages (i.e. 5%, 10% and 15%) by clay weight. Physico-mechanical and thermal properties of brick specimens incorporating agricultural wastes were studied. It was observed that lighter weight bricks can be produced using agricultural wastes, which are helpful in reducing both the cost and overall weight of the structure. Addition of agricultural wastes in burnt clay bricks resulted into reduced compressive strength. However, brick specimens incorporating SBA and RHA up to 15% satisfied the minimum requirement for compressive strength according to different standards for masonry construction. Increase in apparent porosity with decrease in thermal conductivity was also observed with increasing content of SBA and RHA in burnt clay bricks. Substitution of clay by 15% SBA and RHA in the production of burnt clay bricks reduced the thermal conductivity by 31% and 29%, respectively. Microscopic images also showed the presence of interconnected and irregular shaped open pores after addition of agricultural wastes in burnt clay bricks. Based on this study, it can be concluded that the utilization of SBA and RHA (up to 15% by clay weight) in manufacturing of burnt clay bricks is not only helpful in landfill reduction but also leads towards the development of sustainable and thermally efficient construction material.