Purpose: The primary objective of this study is to empirically assess the progress of Poland's energy transition from 2012 to 2022. Design/methodology/approach: The study employs a multidimensional approach using multi- criteria analytical methods. Specifically, the CRITIC and TOPSIS methods were utilized. The CRITIC method was applied to determine the weights of selected indicators that characterize Poland's energy transition process. These indicators include key parameters such as energy efficiency, the share of renewable energy sources in total production, greenhouse gas emissions, and electricity costs. Subsequently, the TOPSIS method was used to develop an index for assessing Poland's energy transition from 2012 to 2022. This index allows for the evaluation of the changes implemented in each year within the study period. Findings: The results indicate that Poland has made significant progress in the energy transformation of its economy. The value of the Energy Transformation Assessment Index has markedly increased in 2022 compared to 2012. This improvement reflects the consistent and effective implementation of pro-environmental policies and measures aimed at the sustainable development of both the energy sector and the national economy as a whole. Practical implications: The developed evaluation methodology offers a universal approach to determining a country's energy efficiency, which can be successfully applied to any country. By utilizing advanced multi-criteria decision analysis methods, this approach considers a broad range of criteria, including energy efficiency, the share of renewable energy sources, greenhouse gas emissions reduction, economic costs, and societal impact. Its versatility allows it to be used for evaluating both individual countries and groups of countries. Originality/value: This paper introduces a novel approach by using MCDM-type methods to assess the effectiveness of a single country's energy transition process. This comprehensive approach provides a holistic assessment of the energy transition, encompassing dimensions of energy security, economic performance, environmental impact, and social outcomes. Keywords: energy transition, process efficiency, energy policy, MCDM methods, multi- criteria analysis. Category of the paper: Research paper.