This paper investigates the stabilization problem for a class of nonlinear systems. An event-triggered controller is proposed to achieve semi-global stability. It only utilizes sampled states of the extended state observer and updates its value when the triggering condition is satisfied. As a result, the communication burden is greatly reduced. The states of the closed-loop system are ultimately bounded by choosing a suitable triggering threshold. A numerical example is included to illustrate the effectiveness of the theoretical results.