The energy sector plays a crucial role for the socio-economic development all over the world. The aim of this study is to synthetically assess the financial efficiency of public energy companies (in this study represented mostly by state-owned companies or their subsidiaries) and compare them with other non-financial public companies (usually private) in the relatively stable decade of 2010–2019 which preceded the COVID-19 pandemic. Our analysis focused on nine energy companies in Poland listed continuously throughout the study period whose complete financial data was available in the Notoria Serwis database. The annual financial performance of each of them was measured by a custom synthetic vector measure of financial efficiency, constructed using 14 financial ratios describing liquidity, leverage, efficiency, profitability and market values as discriminant variables. The results demonstrate that energy companies in Poland do not belong to the cluster of the most financially efficient companies in terms of the applied vector measures. The performance of Lotos and Kogeneracja was improving in the analysed 10-year period, whereas in the case of Tauron, Enea and PGE, it was gradually deteriorating.