This study explores the effects of economic complexity and energy security risk on measures of energy efficiency, namely energy intensity and carbon intensity, for a panel of the 25 top energy use countries. The empirical results from quantile regression analysis for the full panel of countries shows that an increase in economic complexity raises energy efficiency through lower energy intensity and carbon intensity. An increase in energy security risk raises energy intensity with the impact on carbon intensity varying across quantiles. Disaggregating the results between high-income and middle-income countries reveals there are clear differences in the impact of economic complexity and energy security risk on both energy intensity and carbon intensity. Finally, policy discussion and recommendations are provided in the context of the United Nations sustainable development goals.