Smart Urban Metabolism is a hybrid approach – where technological, economic, social and environmental perspectives are simultaneously considered – to feed and improve the circularity of flows within urban contexts. In a global era characterised by intense and pervasive urbanization and datafication, the digital technologies-­‐‐driven approach is becoming decisive among cities around the world engaged in the transition towards a smart and sustainable urban metabolism. In this regard, tools such as real-­‐‐time monitoring stations, GPS tracking systems, sensors, radars, drones, cloud computing, artificial intelligence, augmented reality, smart grids, big data analytics, Internet of Things, and so on, have been recognized as enabling factors for improving the quality and efficiency of urban metabolism circularity. Therefore, these fixed and mobile digital devices make Smart Urban Metabolism a strategic framework for policymakers, urban planners and managers in order to collect, monitor, elaborate and analyse data and information regarding circularity performance within the economic, environmental, social and technological spheres of cities. The following Thesis investigated the contribution of the digitalisation of the circularity of urban metabolism in the improvement of decision-­‐‐making processes of natural and artificial urban resources. Specifically, three research objectives were identified: (1) what digital technologies are capable of improving circularity within the various dimensions of urban metabolism? (2) It is necessary to plan and develop urban technological infrastructures such as sensors, monitoring stations and tracking systems? and (3) What are the social, economic, environmental and technological challenges that emerge from the digitalisation of the circularity of urban metabolism? In order to achieve these research objectives, the study was based on an extensive and detailed literature review on urban digital technologies and on a multiple analysis of case studies of cities considered to at the forefront worldwide of urban metabolism circularity driven by technology. The proposed Smart Urban Metabolism, enabled by the emerging context of circular cities, provides a perspective of social, economic and environmental performance with greater spatial-­‐‐temporal resolution, characterised by data and feedback processed continuously and in real-­‐‐time. One of the most interesting insights that emerge from Smart Urban Metabolism is that this new perspective overcomes some of the limitations identified in the traditional concepts of urban metabolism and urban smartness. The results confirm that there are under-­‐‐ treated social, economic, environmental and technological aspects that can be discovered and analysed through the digitalisation of the circularity of urban processes and operations. Therefore, taking these aspects into consideration in the planning, monitoring and evaluation phases of circularity can lead to the identification of appropriate strategies and practices for the development of smart and sustainable urban metabolism.