We employ the minimal geometric deformation approach to gravitational decoupling (MGD-decoupling) in order to generate an exact anisotropic and non-uniform version of the ultracompact Schwarzschild star, or "gravastar", proposed by Mazur and Mottola. This new system represents an ultracompact configuration of radius R_S = 2M whose interior metric can be matched smoothly to a conformally deformed Schwarcschild exterior. Remarkably, the model satisfies some of the basic requirements to describe a physically acceptable stellar model, such as a positive density everywhere and decreasing monotonously from the centre, as well as a non-uniform and monotonic pressure.