This book constitutes the proceedings of the 4th International Conference on Blockchain, ICBC 2021, held as part of SCF 2021, held as a Virtual Event, during December 10–14, 2021. The 8 full papers and 1 short paper presented were carefully reviewed and selected from 31 submissions. They deal with all topics regarding blockchain technologies, platforms, solutions and business models, including new blockchain architecture, platform constructions, blockchain development and blockchain services technologies as well as standards, and blockchain services innovation lifecycle including enterprise modeling, business consulting, solution creation, services orchestration, services optimization, services management, services marketing, business process integration and management.