This book constitutes the refereed proceedings of the Third International Symposium on Ubiquitous Networking, UNet 2017, held in Casablanca, Morocco, in May 2017. The 56 full papers presented in this volume were carefully reviewed and selected from 127 submissions. They were organized in topical sections named: context-awareness and autonomy paradigms; mobile edge networking and virtualization; ubiquitous internet of things: emerging technologies and breakthroughs; and enablers, challenges and applications. .