Background: Life-cycle assessment (LCA) is a comprehensive method used to evaluate the environmental effects throughout the entire lifespan (from creation to disposal) of a product or process. In this study, we conducted an analysis of the environmental impact associated with generating 1 kilowatt-hour of electricity in a combined-cycle power plant located in the southwest region of Iran. Methods: An LCA following ISO 14044 standards was conducted via the ReCiPe method evaluating 10 impact categories at the midpoint level, and covering the entire life cycle. This method was selected for its comprehensive modeling of potential impacts from numerous chemicals and its practicality at both midpoint and endpoint levels. Results: The study found that resource availability (RA) has the highest impact at 53% in endpoint categories, mainly due to natural land transformation (NLT) and fuel depletion (FD). Human health (HH) contributes 43%, while ecosystem diversity (ED) has a minor 4% role. In midpoint categories, over 99% of global warming potential (GWP) and climate change (CC) are from CO2 emissions due to fossil fuel combustion. Conclusion: Midpoint analysis identified NLT, FD, CC, freshwater ecotoxicity, terrestrial ecotoxicity, human toxicity, photochemical oxidant formation, terrestrial acidification, freshwater eutrophication, and water depletion as the most impacted categories by the power plant. However, at the endpoint level, RA, HH, and ED were the primary concerns. Fossil fuel use significantly shaped the environmental impact throughout the power plant’s life cycle.