This book presents the proceedings of the 20th International Symposium on Advances in Robot Kinematics (ARK2026), held in Barcelona, June 28 – July 2, 2026. It features peer-reviewed contributions from leading researchers worldwide, covering cutting-edge advances in the theory and applications of robot kinematics, motion planning, and mechanism design. From innovative computational methods to novel robotic systems, this volume captures essential developments shaping the future of motion in robotics. As a volume in the Springer Proceedings in Advanced Robotics (SPAR) series, it offers a unique, focused reference for researchers, engineers, and graduate students working at the forefront of kinematic analysis and synthesis.