An adaptive nonlinear trajectory tracking design for mobile robot and its practical implementation are presented in this paper. The design objective is to specify one nonlinear controller with a parameter adaptive law that satisfies the adaptive H2 optimal performance. In general, it is hard to obtain the closed-form solution from this nonlinear trajectory-tracking problem. Fortunately, based on the property of the trajectory tracking system of the nonholonomic mobile robot, the adaptive H2 trajectory tracking problems can be reduced to solving one nonlinear time varying Riccati-like equations. Furthermore, one closed-form solution to this nonlinear time varying Riccati-like equation can be obtained with very simple forms for the preceding control design. Finally, there are two practical testing conditions: circular and S type reference trajectories are used for performance verification.