This study develops a green transition assessment framework using factor analysis to evaluate green development performance in China and nine Southern European Mediterranean countries. Drawing on economic, environmental, and social indicators, it constructs a composite score model to rank countries based on their progress in the green transition. The analysis identifies key drivers such as industrial structure, renewable energy adoption, and technological investment. The findings reveal significant disparities among countries, shaped by resource endowments, policy effectiveness, and energy structures. Based on these insights, the study offers strategic recommendations for strengthening sustainability efforts through green finance, low-carbon technologies, and enhanced international cooperation. Ultimately, it aims to support informed policy-making and foster global collaboration toward a just and effective green transition that transcends mere regulatory compliance.