This paper proposes a multidisciplinary design approach of piezoelectric actuator and control system for smart structures that have a characteristics variation. The system is composed of piezoelectric actuator array and scheduled controller. The control system is designed according to the H₂ specification with a reduced-order modal model. An adaptive control is conducted by scheduling the actuators and the controllers to keep the stability and performance against the characteristics variation of the system. The design problem for improving the H₂ performance is defined, and then the piezoelectric array and the scheduled control system are integratedly optimized by the presented approach, resulting in an enhanced performance for the vibration control. As an example, this strategy is applied to the beam-type smart structure that changes its length.