This two-volume set constitutes the proceedings of the 20th International Symposium, ISVC 2025, held in Las Vegas, NV, USA, during November 17&19, 2025. The 54 full papers and 18 poster papers were carefully reviewed and selected from 118 submissions. The papers cover the following topical sections: Part I: Deep Learning; Computer Graphics; Motion and Tracking; Applications; Object Detection and Recognition; Medical Imaging, and Virtual Reality. Part II: Segmentation; 3D; Recognition; Video Analysis and Event Recognition; Biometrics; Visualization, and Poster.