This paper is on designing a multi-objective, robust parameter space steering controller for yaw stability improvement of a light commercial vehicle and its testing on a hardware-in-the-loop steering test rig. A linear single track model of the light commercial vehicle is used for controller design while its nonlinear version is used during hardware-in-the-loop simulations. The multi-objective design method used here maps D-stability, mixed sensitivity and phase margin bounds into the parameter space of chosen disturbance observer based steering controller filter parameters. The resulting controller design is tested using offline and hardware-in-the-loop simulations. A hardware-in-the-loop simulation test rig with the actual rack and pinion mechanism of the light commercial vehicle under study was built for this purpose. The steering control actuator is placed on the second pinion of the double pinion steering test system used. The hardware and geometry of the steering test rig are identical to the implementation of the steering system in the test vehicle. Unnecessary and expensive road testing is avoided with this approach as most problems are identified and solved in the hardware-in-the-loop simulation phase conducted in the laboratory where the steering subsystem and its controller exist as hardware and the rest of the vehicle being implemented exists as real time capable software. Hardware-in-the-loop simulation results show the effectiveness of the controller design proposed in this paper in tracking desired steering dynamics and in rejecting yaw disturbance moments.