Urban sustainability is one of the most prominent challenges in the global agenda waiting to be addressed since the Earth Summit in Rio de Janeiro. This research work applies a composite indicator that has been developed as the Sustainable Development of Energy, Water and Environment Systems Index to benchmark the performance of a new sample of 26 world cities. The sample advances the geographical diversity of previous samples and represents cities in the Global Covenant of Mayors for Climate and Energy as well as the C40 initiative. The benchmarking results are analysed based on quartiles of city performance and Monte Carlo simulations. The results indicate the top three cities in the sample to be Copenhagen, which obtains a score of 36.038, followed by Helsinki and Gothenburg. The top cities represent multiple best practices including those in district energy networks, water quality, and environmental management. A normative scenario up to the year 2050 is then applied to one of the cities in the sample, namely Rio de Janeiro. The normative scenario involves targets that take place in local plans, particularly Vision Rio 500. The benchmarking results for the new sample of 26 world cities and the normative scenario not only identifies the benchmark leaders but also underlines opportunities to pursue pathways in which higher levels of performance can be reached by cities that may face multiple challenges. The results of the research work holds significance for advancing the application of an original composite indicator to benchmark cities towards supporting the aim of decoupling economic growth from environmental pressures in more sustainable urban systems towards carbon neutrality.