This book constitutes the refereed proceedings of the 21st IFIP WG 5.5 Working Conference on Virtual Enterprises, PRO-VE 2020, held in Valencia, Spain, in November 2020. The conference was held virtually. The 53 full papers were carefully reviewed and selected from 135 submissions. They provide a comprehensive overview of major challenges and recent advances in various domains related to the digital transformation and collaborative networks and their applications with a strong focus on the following areas related to the main theme of the conference: collaborative business ecosystems; collaborative business models; collaboration platform; data and knowledge services; blockchain and knowledge graphs; maintenance, compliance and liability; digital transformation; skills for organizations of the future; collaboration in open innovation; collaboration in supply chain; simulation and analysis in collaborative systems; product and service systems; collaboration impacts; boosting sustainability through collaboration in Agri-food 4.0; digital innovation hubs for digitalizing European industry; and collaborative networks for health and wellness data management.