<p>This paper proposes the design of an observer-based adaptive integral sliding mode control strategy for a class of nonlinear uncertain switched systems with unmeasurable states. During the controller design process, the information of model uncertainties, as well as the bounds of the nonlinear and external disturbance, is assumed to be unknown. By using the estimated system states, a novel integral-type sliding surface is constructed, and a corresponding adaptive sliding mode controller is developed. The proposed controller not only mitigates the chattering induced by subsystem switching but also guarantees finite-time reachability of the sliding surface. A switching signal, designed based on both time and state, is incorporated to optimize the switching logic. By employing Lyapunov theory and the linear matrix inequality (LMI) technique, sufficient conditions are established to ensure the stability of the overall closed-loop system under the proposed control scheme. Numerical simulations validate the effectiveness and feasibility of the proposed method in suppressing uncertainties and external disturbances.</p>