The study investigated the changes that occurred in the Mexican power sector pre-, during, and post-COVID-19 pandemic and its repercussions on energy sustainability goals. The study is based on the variability of the installed capacity, consumption, generation, and demand of the National Electric System (SEN), covering the period from 2017 to 2021. The data were collected from the Development of the National Electric System (PRODESEN), the Ministry of Energy, the National Energy Balance, and the government's official website. The results indicated that in-stalled capacity and generation increased by 22.83% and 27.86%, respectively, despite the pan-demic. This growth was attributed to clean energy, mainly photovoltaic solar and wind sources. Another finding is that the gross domestic product (GDP), consumption, and demand were seri-ously affected by COVID-19. They had a fall of 8.2%, 2.2%, and 4.4%, respectively, which trans-lates into a significant economic lag and a slowdown in energy self-sufficiency and the Mexican Energy Transition (TEM). Moreover, the objective of generating 35% and 40% of electrical ener-gy through clean energy will be achieved by 2031 and 2035, instead of 2021 and 2035, respec-tively.