This book constitutes the proceedings of the 20th International Conference on Perspectives in Business Informatics Research, BIR 2021. The conference was held during September 22-24, 2021.The 16 papers presented in this volume were carefully reviewed and selected from 49 submissions. They were organized in topical sections as follows: Technology adoption and acceptance during COVID-19 times; conceptual modeling for enterprise systems; enterprise modeling methods and frameworks; compliance and normative challenges; and empirical investigations on digital innovation and transformation prerequisites.