The aim of this study is to examine the relationship between firm value and the ESG performance of European listed small-capitalized energy firms for the 5-year period 2017–2021. To study this relationship, we employ panel data models. In our model the dependent variable—that is, firm value—is proxied by Tobin’s Q, while our main independent explicative variable is represented by the ESG performance of firms, proxied by ESG ratings provided by Refinitiv Eikon. We test a model considering the ESG combined score as a proxy for ESG performance. To investigate which of the three pillars impacts most the firm value, we carry out an additional model in which the main independent variables are represented by the individual environmental pillar score, social pillar score, and governance pillar score. As empirical literature is mainly focused on large-capitalized firms, by investigating small-capitalized firms we add knowledge to the literature stream focused on the hypothesized association between firm value and ESG performance. The findings reveal that overall ESG performance as well as environmental performance positively impacts the firm value of energy firms. The results do not provide evidence of the association between social and governance performance and firm value.