This paper addresses a robust control methodology to enhance the power system stability and voltage regulation as an integrated design approach. The automatic voltage regulation and power system stabilizer design problems are reduced to solve a single H∞-based static output feedback control problem. To determine the optimal gains, an iterative linear matrix inequalities (LMI) algorithm is used. To demonstrate the efficiency of the proposed control strategy, an experimental study has been performed for a four-machine infinite-bus system at the Research Laboratory of the Kyushu Electric Power Co. in Japan. The proposed robust technique is properly shown to maintain the robust performance and minimize the effects of disturbances.