Hip disarticulation is a highly mutilating intervention, which consists in amputating a whole leg to circumvent the propagation of a bone tumor in the pelvis. Although bionic prostheses for transtibial and transfemoral amputees are rapidly developing nowadays, active hip modules are not part of this research agenda yet. This is likely due to the relatively low incidence of hip disarticulation, and to the intrinsic challenges associated to the interfacing between an amputated subject and a whole artificial leg. In this project, I propose to address three research questions, related to the design, control, and validation of an active leg prosthesis for a disarticulated amputee. First, I will design an innovative active hip prosthesis. Combined with existing knee and ankle modules, this will provide the first full-leg prosthesis having the capacity to continuously deliver mechanical energy through each of its three joints. Secondly, I will design a control strategy to achieve levelground walking by interfacing this device with a disarticulated amputee. This control framework will rely on bioinspired control mechanisms through a neuro-mechanical model of the lower limb, combining reflexes and a descending oscillator. A particular challenges will consist in designing a “steering” (or “pacing”) signal from the detected motion intention of the user, in order to guide the behavior of the prosthesis in symbiosis with the intact segments. A second version of the controller will be designed with specific focus on enhancing the user’s balance. Last but not least, the project will also comprise a strong experimental section, in order to validate the proposed ideas with disarticulated amputees wearing our prototype.