This paper deals with an integrated design interval observer-based Fault Tolerant Control (FTC) for linear time invariant (LTI) system subject to the uncertain modeling, actuator fault and external disturbances. Under the assumption that uncertainties and disturbances are unknown but bounded with priori known bounds, a design method for obtaining Proportional Integral (PI) interval observer that provides guaranteed lower and upper bounds of the state as well as faults is considered. Based on the estimated information, FTC controller is designed to ensure robust stability of the closed-loop system. Sufficient stability conditions with H∞ performance are expressed in terms of Linear Matrix Inequalities. An application to vehicle lateral dynamics is considered to show the effectiveness of the proposed algorithms.