This book constitutes the proceedings of the International Workshop on Shape in Medical Imaging, ShapeMI 2025, which took place in Daejeon, South Korea, on September 23, 2025, held in conjunction with MICCAI 2025.The 26 full papers included in this book were carefully reviewed and selected from 28 submissions. They focus on shape and spectral analysis, geometric learning and modeling algorithms, and application-driven research.