The problem of gain-scheduled H_∞control for networked polytopic systems with bounded rates of parameter variations is investigated. The state transmission delays are handled via state augmentation technique so that a switched polytopic system model is obtained. Considering the bounded variation rates and the parameter transmission delays, a vector polytope model is achieved to describe the triplet of the current, the forthcoming and the delayed parameters. By means of switched parameter-dependent Lyapunov functions, the design criterion of the gain-scheduled H_∞ controller is given in terms of LMIs. The presented method extends existing results for polytopic systems to allow for network-induced delays and qualifies relatively lower conservativeness. A simulation example shows the effectiveness of the proposed approach.