To ensure long-term sustainable access to space, it is of paramount importance that humankind acts to alleviate the space debris problem in near vicinity of Earth. The most effective mitigation strategy for large debris items is provided by active debris removal missions, which remove one or more resident space objects from orbit. The execution of such complex missions comes, however, with distinct technological challenges, which are mainly concerned with the development of an advanced GNC system. Therefore, a GNC system for an active debris removal mission was developed, with a prime focus on a convex guidance system. Results showed that the GNC system can obtain a robust, autonomous, and fuel-efficient execution of the close-range rendezvous phase, by connecting the initial conditions with the final conditions, while adhering to complex path and state constraints.