This book constitutes the proceedings of the 21st International Semantic Web Conference, ISWC 2022, which took place in October 2022 in a virtual mode.The 48 full papers presented in this volume were thoroughly reviewed and selected from 239 submissions. They deal with the latest advances in fundamental research, innovative technology, and applications of the Semantic Web, linked data, knowledge graphs, and knowledge processing on the Web.  Papers are organized in a research track, resources and in-use track. The research track details theoretical, analytical and empirical aspects of the...