The depletion of fossil fuels and insufficient solid waste management have become pressing concernsdriven by their high demand in the modern world. Tonnes of waste chicken bone (WCB) and waste cooking oil(WCO) are being deposited in landfills, posing significant environmental pollution and health risks to humans.Hence, this presents an ideal opportunity to repurpose these materials. In this study, heterogeneous Ca2+ and Fe3+ -supported calcium oxide (CaO) catalysts from WCB were produced using a simple wet impregnation method. XRayDiffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM), X-ray Fluorescence (XRF)and N2 Adsorption/desorption were used to characterize the newly synthesized catalysts and investigate theirphysicochemical properties. A series of analyses was conducted to compare the catalytic activity of 10 wt% Ca-CaO,10 wt% Fe-CaO and CaO catalysts in the transesterification of WCO to produce biodiesel with the reactionparameter of 1 wt% catalyst loading, 10:1 methanol-to-oil molar ratio and 4 h reaction time. It is found that thehighest yield of fatty acid methyl ester (FAME) also known as biodiesel was obtained for 10 wt% Fe-CaO (72.52%),compared to 64.73% for 10 wt% Ca-CaO and only 40.53% for CaO, which is due to excellent acidic and basic activesites from the combination of transition metal oxides (Fe3+) and base metal oxide (CaO). Therefore, this studydemonstrates that the Fe3+ modified CaO catalyst used in biodiesel production is not only cost-effective but also holdsthe potential to mitigate waste production, thereby aligning with a global sustainable approach towards a greenerearth.