Abstract: The authors studied the problem of guaranteed cost controller design for a class of switched singular systems with both state and input delays.A new sufficient condition of the existence of guaranteed cost state feedback controllers was derived for the systems by constructing the generalized Lyapunov function and taking the linear matrix inequality approach.Furthermore,the problem of the guaranteed cost controller design could be turned into the solvable problem of a set of linear matrix inequalities.Finally,a numerical example was given to show the potential of the proposed technique.