This book constitutes the refereed proceedings of the 20th International Conference on Mobile Web and Intelligent Information Systems, MobiWIS 2024, held in Vienna, Austria, during August 19-21, 2024. The 21 full papers and 1 short paper included in this book were carefully reviewed and selected from 65 submissions. They were organized in topical sections as follows: IoT, networks and cloud services; AI, blockchain and security; blockchain techniques and technologies; AI-based applications; and smart cities and knowledge management.