This paper proposes a plug-and-play decentralized control approach for voltage and frequency stabilization in islanded AC microgrids consisting of multiple power-electronics-interfaced distributed generation (DG) units. The proposed control strategy guarantees stability and desired H∞ level in voltage tracking performance of islanded microgrids. The line-independent characteristic of the proposed voltage control scheme facilitates the plug-and-play operation of DG units. The simulation results in MATLAB/Simscape Electrical environment demonstrate the suitability of the proposed voltage control technique for islanded AC microgrids with flexible structures.