This book presents the proceedings of the 3rd International Conference on Wireless Intelligent and Distributed Environment for Communication (WIDECOM 2020), sponsored by Ryerson University, Toronto, Canada, May 6-8, 2020. The WIDECOM conference solicits papers addressing issues related to new dependability paradigms, design, and performance of dependable network computing and mobile systems, as well as issues related to the security of these systems. The goal of the conference is to provide a forum for researchers, students, scientists and engineers working in academia and industry to share their experiences, new ideas and research results in the above-mentioned areas.