In this paper, an adaptive fuzzy output feedback control approach with prescribed performance is proposed for a class of uncertain nonlinear strict-feedback systems with unmeasured states. With the help of fuzzy logic systems identifying the unknown nonlinear system, a fuzzy state observer is established for estimating the unmeasured states. Under the framework of the backstepping control design and incorporated by the predefined performance technique, a new adaptive fuzzy output-feedback control method is developed. It is shown that all the signals of the resulting closed-loop system are bounded and the tracking error remains an adjustable neighborhood of the origin with the prescribed performance bounds. The simulation examples and comparison with the previous control methods are provided to show the effectiveness of the proposed control approach.