In this study, based upon designing a novel observer for Markovian jump systems (MJS), the state and fault estimation problem in the presence of simultaneous sensor and actuator faults in MJS is investigated. The novel observer is a linear descriptor reduced-order one. By employing the proposed linear descriptor reduced-order observer with decoupling technology, the estimation of state and sensor fault can be obtained directly without any supplementary design. Compared with the traditional sliding mode observers in MJS, the advantage is that the sliding surface switching problem is avoided. Finally, a practical example of mobile manipulators is given to illustrate the effectiveness of the theoretical results.