The present paper develops an output feedback fixed-time sliding mode control (FxTSMC) approach for lateral trajectory tracking of an autonomous vehicle subject to disturbances. Firstly, a nonsingular terminal sliding manifold is constructed to force the orientation error and lateral deviation to converge to desired values in finite time. Secondly, using variable exponent coefficients, a switching control law is proposed to provide fixed-time stability against external disturbances. By adjusting the control design parameters, the upper bound of the settling time for the closed-loop lateral system can be attained arbitrarily minimal without depending on the systems initial conditions. The effectiveness of FxTSMC is demonstrated by comparing the performance of closed-loop systems of the supplied controller and other existing controllers.