Abstract Since the introduction of Malaysia's own Four-Fuel Diversification Policies 1981, and the updated Five-Fuel Diversification Policies in 2001, no studies have been conducted to measure and evaluate the success and progress of these policies. This study aims to address this issue by quantitatively measuring the extent of fuel diversification in Malaysia since the conceptualisation of these policies in 1981 through the Herfindahl-Hirschman Index and supported by an analysis through the Shannon-Weiner Index. Statistical data from the Malaysia Energy Commission on the Primary Energy Supply and Final Energy Demand were chosen for this purpose. The findings suggest that whereas Malaysia has managed to reduce its over-dependency on crude oil/petroleum as its primary fuel, this dependency has been replaced partly by a dependency on natural gas, on the supply side. As for the demand side, the transportation sector's continuing dependency on petroleum has also affected the level of fuel diversification. Thus, the level of fuel diversification, while having shown improvement, was less than expected. Further incorporation of renewable energy in the future may hold the key to a genuine and more successful energy diversification for Malaysia.