The environmental, social, political, and economic issues have pushed worldwide economies to implement the principles of sustainable development. Given the high impact of the built environment on the planet, people, and economy, the real estate has increased its interest in adopting sustainable strategies to ensure the sustainable development of the sector. The idea of evaluating sustainable performance throughout indicators is discussed both in the academia and in the market. Especially, new indicators, named Environmental, Social, and Governance (ESG), emerged as good practices to implement evaluation assessments of sustainable performances. Offering a practical and transparent way to measure sustainability, the adoption of ESG indicators in the real estate is still an emerging topic. Although several frameworks have been developed in the market, few academic studies have tried to reason about the ESG measurement of requalification projects in the real estate market. Indeed, the high rumours received by ESG do not mean that the real estate turned into a sustainable sector. With the objective to highlight the potential in adopting an ESG framework to address sustainable practices in real estate operations, the present research implements a measurement model. The implemented framework, called ESG Measurement Tool, uses the Analytic Hierarchy Process (APH) to classify the measurement indicators throughout a weight matrix. By evaluating 52 indicators, divided into six clusters (Site, Territory, Services, Material—Technologies, Energy—Emissions, Water, Wellbeing, Social—Economic, and Governance), the framework aims to address designers and investors during a requalification project in the real estate. After defining the way to evaluate the 52 indicators, a case study project is selected to evaluate the effectiveness of the framework. The requalification project converted an industrial building, located into the city centre of Milano (Italy), into luxury residences. The application on a real case study project allows this study to improve the evaluation process of the ESG Measurement Tool and improve the effectiveness of reporting results. In the discussion, the present research presents the improved framework of the ESG Measurement Tool by integrating the results of the case study application. The ESG Measurement Tool represents a practical and transparent framework to support the transition towards sustainability of requalification projects in the real estate sector. By evaluating the environmental, social, and governance impact, the case study application demonstrates the easiness of applying the implemented framework during the decision stage of requalification projects. Future improvements will focus on applying the framework to different buildings in order to define benchmarks that will support comparison analysis.