This book constitutes the refereed proceedings of the 26th International Conference on Distributed Computer and Communication Networks: Control, Computation, Communications, DCCN 2023, held in Moscow, Russia, during September 25-29, 2023. The 37 full papers and 4 short papers included in this book were carefully reviewed and selected from 122 submissions. They were organized in topical sections as follows: Distributed Systems Applications; Analytical Modeling of Distributed Systems; Computer and Communication Networks.