With technological development, the use of modern methods in producing biofuels, especially biodiesel, has become necessary to make the process more sustainable and time-efficient. In this study, the feasibility of biodiesel production from waste cooking oil using CaO nanocatalyst produced from mango fallen leaves extract with the aid of microwave was explored. The effect of key parameters such as microwave power, methanol to oil w/w ratio, reaction time, and catalyst loading was studied. The results demonstrated that the highest yield of 96% was obtained at 10% microwave power at 15 minutes, 40% methanol to oil w/w ratio, and 3% catalyst loading. In addition, the augmentation in the temperature may cause to reduced yield of biodiesel. The physical and fuel characteristics of the produced biodiesel were measured; it had a viscosity of 5 mm2/s, a density of 0.889 g/cm3, and a flash point of 130 °C. In addition, the produced biodiesel was characterized by FTIR and gas chromatography-mass spectrometer (GC-MS) analysis which ensured the presence of methyl ester