This research uses the slack‐based measure data envelopment analysis to compute the energy and emission efficiencies of Association of Southeast Asian Nations (ASEAN) and other Asian economies during the 2001–2017 period, employs the Malmquist productivity index to check for the main source of efficiency score changes due to technical changes, and then applies panel Tobit regressions to determine the factors explaining the efficiencies. Our empirical results show that the energy efficiency scores of ASEAN economies had been catching up to other Asian economies after the Global Financial Crisis, whereas the emission efficiency scores of various ASEAN economies had been falling behind other Asian economies over the same period. The main source of efficiency score changes over time is efficiency changes and not technical changes. Decreases in the fossil fuel ratio of net electricity generation and the secondary industry ratio within total industry improve both lead to improvements in energy and emission efficiencies.