Abstract: Proportional Integral Observer (PIO) for tracking a nonlinear method has a lower sentiency to cipher the state and output variables. So, a more nonlinear controller has to be else to control to activity. In this study, a fuzzy logic (FLC) controller has been added to the PIO to meliorate the calculation transmute. A Fuzzy Proportional Integral Observer (FPIO) for following a nonlinear system has been premeditated to decimate the susceptibleness to cipher the tell and turnout variables with the existent posit and product variables. The FPIO controller has been tested for improving the estimation control using a nonlinear quarter vehicle active suspension system with a nonlinear hydraulic actuator. A comparison simulation of the proposed nonlinear system for estimating the state variables and tracking the output (suspension deflection) with a set point bump road disturbance using FPIO and PIO. The comparison simulation result shows that the estimated state variables and system output match the actual ones perfectly using a fuzzy PIO controller.