This book delves into dynamic modeling, control strategies, and theoretical foundations of underactuated robotic systems. Designed for robotics researchers, graduate students, and professionals, it guides them to: understand fundamental principles governing underactuated systems and their nonlinear dynamics, and use cutting-edge control techniques, such as feedback linearization, sliding mode control, energy-based methods, and machine learning integration. Focusing on practical applications and making use of case studies and simulation exercises to solidify understanding, this book equips readers with the necessary tools needed to address real-world robotics challenges.