In the last four decades, with the increase in population levels at geometric pace and frenetic economic activity, there has been a tremendous rise in energy consumption globally. Since energy production and utilization generate undesirable greenhouse gas (GHG) in most of the cases, global economies are facing a dual challenges of maintaining energy security and minimising environmental impact of energy under control. Therefore, achieving economic growth with improved energy efficiency becomes imperative. Against this backdrop, three major objectives have been ascertained in the current work: firstly, environmental energy efficiency (EEE) - defined as energy efficiency measures incorporating undesirable output in the production process – is estimated at the global level. Under the broad framework of data envelopment analysis (DEA), the traditional input-oriented measures of efficiency, the joint production approach and the latest by-production approach have been used to assess EEE. In the process of achieving higher energy efficiency economies may achieve higher total factor productivity through innovation. Higher energy may also lead to lower TFP if stern regulatory restrictions are imposed on energy utilization. Therefore, the second objective of the study is to examine the impact of improved energy efficiency on total factor productivity (TFP), where the latter is considered as an indicator of economic performance. DEA-based Malmquist productivity index has been used to compute TFP. The hypothesis of the second objective is that energy efficiency may impact TFP differently at different points of the productivity distribution, indicating a non-linear relationship between the two. Quantile regression for panel data (Powell, 2016) have been utilised to estimate the relationship between energy efficiency and TFP, controlling for several country-specific factors at the global level. A reduction in global level emission requires all the economies to converge to a higher level of efficiency. This may happen due to knowledge and technology spillover from high-income economies to middle and low-income economies. Therefore, the possibility of convergence in energy efficiency at the global level is also examined using the approaches of meta-frontier technique as well as the traditional convergence tests. All the objectives have been analysed encompassing a sample of high-income, middle-income and low-income economies for the period 1993-2013. The empirical results show that there has been a gradual improvement in EEE level except in the years 1998-1999 and 2009. The high-income economies spearheaded this improvement in EEE followed by the middle-income and low-income economies. This might be explained by the use of a relatively greater share of renewable energy in high-income economies. The empirical results also confirm a positive impact of energy efficiency on TFP. However, that impact is higher in the lower and higher quantiles of productivity distribution, while it is relatively lower in the middle quantile range of productivity distribution – indicating a ‘middle income trap’ for the middle-income economies. Moreover, the convergence analysis shows that the middle-income economies appear to converge to global EEE levels while low-income economies have lagged behind. Low-income economies seem to show club convergence. This is because technology gap ratio – which captures the closeness of the observed technology of a group of economies’ to the meta-frontier - of middle-income economies are converging towards that of high-income economies whereas low-income economies display a diverging trend especially after the year 2010. The root cause of energy inefficiency at the global level is poor management. Energy efficiency at the global level have shown neither conditional nor unconditional convergence.