This work proposes a novel robust controller in Linear Matrix Inequality framework for a singlemachine infinite bus system. The mathematical equations defining the system are highly nonlinear. The novelty of the paper is the linear control law, which is obtained without linearizing the system. Along with thenonlinearity here, another two contingencies are also taken into account—(i) uncertainties in terms of parameter variations and losses and (ii) time delay in the feedback control law. The proposed controller is expected to accommodate the parameter uncertainties and the time delay. Simulation results support the analytical findings