This book constitutes the refereed post-conference proceedings of the Third International Conference on Future Access Enablers for Ubiquitous and Intelligent Infrastructures, FABULOUS 2017, held in Bucharest, Romania, in October 2017. The 37 revised full papers were carefully reviewed and selected from 61 submissions. The main topics deal with future access networks, Internet of Things and smart city/smart environment applications, communications and computing infrastructures, security aspects in communication and data processing, signal processing and multimedia.