A new strategic direction for greening our cities and making them smart to reduce the environmental impact of their performance, increase employment and economic viability, and to enhance the quality of life requires a thorough assessment of sustainability and smart urban performance. This paper considers a database of over 90 global cities including London, New York, Hong Kong, San Francisco, Los Angeles, Sao Paolo, Rio de Janeiro, Buenos Aires, Paris, Berlin, Stockholm, Moscow, Beijing, Seoul, Singapore, Shanghai, Sydney and Tokyo exploring linkages between different sustainability and smart city dimensions. To assess urban sustainability performance, this study applied a multi‐criteria approach using a panel of 20 indicators to a set of 57 global cities. The assessment comprised important aspects of energy transitions, focusing on the drivers of CO2 emissions in cities, including the share of coal in the energy mix, public transport and cycling patterns, waste recycling, the water‐energy nexus, as well as the role of smart and creative economy. The results show that San Francisco leads in economic and environmental priorities, and Stockholm leads in social and smart city priorities. Seoul consistently performs very successfully across the whole spectrum of indicators. We devote considerable attention to the strategies, policies and performance of the leading cities, namely, San Francisco, Stockholm and Seoul. This assessment could be a valuable tool for policy‐makers and investors, and could help identify linkages between different sustainability dimensions, as well as investment opportunities in cities with sustainability potential.