<p>Successful engagement with high-speed ballistic targets is known as a drastically challenging task. In order to obtain a hit-to-kill performance at the terminal phase of engagement, it is required to combine the best hardware (e.g., sensors and actuators) and software solutions (e.g., control and estimation techniques). In this work, we propose a three-dimensional novel integrated guidance and control (IGC) scheme taking advantage of a divert control system as the aiding actuator along with the daisy-chain technique within the terminal phase. An extended Kalman filter is formulated considering an accurate kinematic model for a two-axis gimbaled seeker mechanism. Our scheme can achieve a hit-to-kill performance in the presence of onboard seeker errors, aerodynamic uncertainties, and target maneuvers. This is achieved thanks to utilizing a robust control structure called disturbance observer based control (using reduced order extended state observer), along with an exact seeker filter to accurately estimate the line of sight rates and target acceleration. In contrast with all existing IGC schemes, we have not assumed that the line of sight rates are ideally available. The effectiveness of the proposed strategy is illustrated through numerous simulation analyses against high-velocity targets. It is proved that the proposed method can engage in high-altitude and high zero-effort-miss scenarios using thruster and fin control simultaneously.</p>