A robust governor design using a multivariable-cascade control approach is proposed for hydro turbine speed controls. The non-linear turbine model includes the effects of water hammer, travelling waves, and inelastic water penstocks. Disturbance and parameter uncertainties are briefly discussed to investigate the stability robustness and performance measures of the system. Bounds of the uncertainties in system parameters are required to design the robust governor. Polynomial H. control method is used in the design. The parameterized dynamic weighting functions of the design theory are selected to achieve the required control functions and robustness. The robust governor ensures that the overall system remains asymptotically stable for all bounded uncertainties and for system oscillations. Simulation results show the feasibility of the approach and the factors involved in the design such that the proposed robust governor improves the performance significantly even in the presence of the uncertainties in plant parameters.