In this paper, a novel inner/outer-loop control framework for the pitch autopilot of a tail-controlled, skid-to-turn missile is proposed. The generalized extended state observer (GESO)-based inner-loop design is constructed to estimate the disturbances and uncertainties and simultaneously compensate them in the input channel. In doing so, the uncertainty of the model can be reduced within an appropriate range for robust control design. The outer-loop H design based on mixed sensitivity method acquires the desired closed-loop performance and robustness. The presented H-GESO design is novel in that it combines the powerful disturbance rejection methodology with the effective robust H control technique. Moreover, it neither requires accurate plant model nor any information about the uncertainty and disturbance. Nonlinear simulations are performed to demonstrate the effectiveness of the proposed method. In order to further evaluate the robustness of the presented method, a performance comparison with equivalent-input-disturbance-based control and conventional gain-scheduled H design is also implemented in the presence of parameter perturbations, wind disturbance, actuator characteristics, and measurement noise.