In this paper, networked control systems (NCS) is modeled as a discrete-time linear state-delayed system with norm-bounded uncertainty. Inspired by the so-called descriptor model transformation, a delay-dependent sufficient condition for the existence of a guaranteed cost controller for NCS is presented by a set of linear matrix inequalities (LMIs). The resulting controller can not only asymptotically stabilize the system but also guarantee an adequate level of performance. Theoretical analysis and illustrative results show that the control strategy presented in this paper is effective and feasible.