Application of solid catalysts synthesized from agricultural wastes provides an environmentally benign and low-cost process route to the synthesis of biodiesel. An ash containing equal mixture of cocoa pod husk, plantain peel and kola nut pod husk ashes (CPK) which was obtained by open combustion of each biomass in air and calcined at 500 oC for 4 h. The calcined CPK ash was characterized to determine its catalytic potential. Two-level transesterification technique was used to synthesize biodiesel using the developed catalyst. The process parameters involved were optimized for the microwave-aided transesterification of a blend of honne, rubber seed and neem oils in volumetric ratio 20:20:60, respectively. The study showed that ash derived from combination of various biomass wastes provides a catalyst which consists all necessary catalytic ingredients in their relative abundance. The calcined CPK consists of 47.67% of potassium, 5.56% calcium and 4.21% magnesium attesting to its heterogenous status. The physisorption isotherms reveals that it was dominantly mesoporous in structure made up of nanoparticles. Maximum of 98.45 wt.% biodiesel was obtained through MeOH:oil blend of 12:1, CPK concentration of 1.158 wt.% and reaction time of 6 min under microwave irradiation. Quality of the synthesized biodiesel satisfied the requirements stipulated by standard specifications. Thus, this work demonstrates that blend of agrowastes and mixture of non-edible oils could be used to synthesize quality and sustainable biodiesel that can replace fossil diesel.