This book constitutes the refereed proceedings of the 9th International Symposium on Business Modeling and Software Design, BMSD 2019, held in Lisbon, Portugal, in July 2019. It contains 12 full and 11 short papers. BMSD is a leading international forum that brings together researchers and practitioners interested in business modeling and its relation to software design. Particular areas of interest are: Business Processes and Enterprise Engineering; Business Models and Requirements; Business Models and Services; Business Models and Software; Information Systems Architectures and Paradigms; Data Aspects in Business Modeling and Software Development; Blockchain-Based Business Models and Information Systems; IoT and Implications for Enterprise Information Systems. The theme of BMSD 2019 was: REFLECTING HUMAN AUTHORITY AND RESPONSIBILITY IN ENTERPRISE MODELS AND SOFTWARE SPECIFICATIONS.