In response to the issues of parameter uncertainty and external disturbances in the permanent magnet synchronous motor (PMSM) system, this paper proposes a control strategy based on a fractional-order integral sliding mode observer. This strategy integrates fractional-order calculus theory into the design of the sliding mode observer, leveraging the memory property of the fractional-order integral operator to utilize historical information and thereby improve the observer’s estimation accuracy for system states and disturbances. Meanwhile, integrating the fractional-order integral theory with the sliding mode variable structure control, a new sliding mode controller is designed to solve the problem of high-frequency chattering in traditional sliding mode control. By optimizing the fractional-order integral link in the switching function, the dynamic performance is significantly improved while retaining the strong robustness of the system. MATLAB simulations and experimental results demonstrate that the proposed strategy effectively mitigates the speed fluctuations of permanent magnet synchronous motors, maintains the steady-state error within approximately 0.15 r/min, and exhibits superior anti-interference capabilities compared to conventional methods. These findings validate the efficacy and practical engineering significance of the proposed approach.