SummaryThe main contribution of this article is a new methodology of a polytopic observer‐based controller in estimating and accommodating polynomial actuator degradation for uncertain stochastic linear parameter varying system. In this design, robust observer‐based controller gains are synthesized with a unique linear matrix inequality solution such that the impact of disturbance on observer estimation is attenuated by a frequency‐shaping filter, while ensuring the closed‐loop stability against system uncertainties and stochastic noise. Finally, an example is illustrated to highlight the performance of the proposed method.