This work deals with the design and experimental evaluation of a passive/active cantilever beam autoparametric vibration absorber mounted on a two-story building-like structure (primary system), with two rigid floors connected by flexible columns. The autoparametric vibration absorber consists of a cantilever beam with a piezoelectric patch actuator, cemented to its base, mounted on the top of the structure and actively controlled through an acquisition system. The overall system is then a coupled nonlinear oscillator subjected to sinusoidal excitation in the neighborhood of its external and internal resonances. The addition of the piezoelectric patch actuator to the cantilever beam absorber makes active the passive vibration absorber, thus enabling the possibility to control its equivalent stiffness and damping and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies and parametric uncertainty.