This paper deals with the H∞ robust output control for vehicle dynamics where the sideslip angle is unavailable for measurement. This study uses the multiple model approach to represent the vehicle model. The road adhesion conditions change and modeling errors are taking into account by introducing uncertainties. Thus, giving a nonlinear vehicle model, its representation by a multiple model is discussed and validated using vehicle simulator software CarSim. Next, based on the uncertain multiple model of the vehicle, an H∞ controller based on observer is developed. The closed loop stability conditions of a vehicle with the controller and the observer are parameterized in terms of Linear Matrix Inequality (LMI) problem. Numerical simulations of the vehicle handling with the developed observer and controller have been carried out using CarSim simulator. The results obtained indicate that considerable improvements in the vehicle handling can be achieved whenever the vehicle is governed by the proposed H∞ observer-based controller.