This book constitutes the refereed proceedings of the 12th International Conference on Graph Transformation, ICGT 2019, held as part of STAF 2019, in Eindhoven, The Netherlands, in July2019.The 12 research papers and 1 tool paper presented in this book were carefully reviewed and selected from 22 submissions. The papers deal with the following topics: Theory, Analysis and Verification, Tools and Applications, and Transformation Rules Construction and Matching.