To counteract the growing transport needs of quickly developing metropolises, city metro system modernization is a matter of utmost urgency. As technology and systems continue to develop over time, the implementation of computerized multicriteria decision-making algorithms would definitely improve decision-making processes concerning the metro system modernization. This research aims at addressing digitalization in alternative selection processes in the context of the Cairo Metro modernization project. The overall objective is to offer a systematic but efficient procedure for choosing the more feasible alternatives in the rehabilitation of a system. The multicriteria decision-making model to be utilized integrates quantitative and qualitative criteria (cost, construction time, environmental impacts, passenger satisfaction, and technical feasibility), along with the priorities and preferences of the key stakeholders—metro transport authorities, urban planners, engineers, and the general public. The digitalization process entails data collection and assessment of enormous amounts of data originating from various sources, such as metro performance indices, passenger commentaries, environmental surveys, and cost analysis. The approach is validated using real data from the Cairo Metro system. The results validate the efficiency and effectiveness of the algorithm in selecting the best alternatives for modernization. With computerization of the decision-making, the subjectivity diminishes, transparency is enhanced, and combination of different opinions becomes easier. This study also takes up the topic of city metros’ modernization by putting forth a comprehensive model that computerizes the alternative processes. The experience gained from this project can benefit the individual transport authorities, city planners, and policymakers in modernizing the metros, especially the developing nations that are facing the same challenges. The proposed multicriteria decision-making algorithm can also be applied and adjusted in other parts of the world with regard to metro modernization plans to develop more efficient and sustainable urban public transportation systems.