A robust individual pitch control strategy is presented to deal with periodic load disturbances on wind turbines under operating point variation. The asymmetric loads are mainly caused by the tower shadow and wind shear effects. Multi-blade coordinate (MBC) transformation is utilized to model the turbine dynamics under various operating points. The coupling dynamics of the multi-input multi-output (MIMO) system are considered to reveal high harmonic frequency peak reduction. The stability and robustness performance of the system under uncertainties are guaranteed by robust control design. The performance of the synthesized controller is compared with a collective controller and a PI individual controller. The results show significant load mitigation in periodic frequencies.