Whether empowering leadership promotes employee’s performance has attracted much attention. However, this body of literature found mixed results these years. The seemingly contradictory findings suggest that there may be a complex relationship between these two variables. To address the ambiguity and the lack of clarifying in empowering leadership research, this paper presents a curvilinear prediction. Drawing on the cost of task autonomy and self-determination theory, we examined a potentially inverted U-shaped relationship between empowering leadership on employee’s task performance, as well as the mediation effect of sense of self-determination in the relationship in the context of Chinese organizations. Data was collected from 550 full-time employees and their immediate leader from a variety of industries in Shandong, Beijing and Hebei. 478 matched data were available, yielding an effective response rate of 86.91%. Cronbatch’s alpha coefficients showed acceptable reliabilities of all measurements. Among the variables, empowering leadership, sense of self-determination and demographic variables were collected from employees, while task performance was gathered from their immediate leaders. Following prior studies, we controlled employees’ gender, age, education and dyadic tenure with their leaders, to rule out alternative explanations. Correlation analysis, confirmative factor analysis, hierarchical regression modeling and bootstrapping analysis were used to test the hypotheses. We adopted SPSS 21 and Mplus7.0 software to do the analysis. Consistent with our hypotheses, regression results revealed that: (1) Empowering leadership had an inverted U-shaped relationship with task performance, such that the relationship was positive for low to moderate levels of empowering leadership, and negative for moderate to high levels of empowering leadership. (2) Empowering leadership and sense of self-determination were positively related. (3) Sense of self-determination had an inverted U-shaped relationship with task performance. (4) The relationship between empowering leadership and task performance was mediated by sense of self-determination. These results highlighted the too-much-of-a-good-thing effect (TMGT effect) of empowering leadership, whereby the positive impact on task performance reach inflection points at which the impact turns negative, through facilitating sense of self-determination as the mediation mechanism. The current study provides three theoretical contributions: first, this study investigates the relationship between empowering leadership and task performance under Chinese culture backgrounds. Besides, integrates two competing effects of empowering leadership on employee’s task performance, which extends the literature of TMGT effect in the field of organizational behavior. Furthermore, we clarify the influencing mechanism of this influence, revealing that sense of self-determination also has an inverted U-shaped relationship with task performance, thereby mediates main effect. Meanwhile, this study also offers managerial implications that both excessive and defective power sharing will be detrimental to employees’ task performance, therefore managers should limit the application of empowerment to avoid the negative outcomes. This study has several limitations and could be improved in future studies. First, the present study is cross-sectional, which restrict the casual inferences. Future studies could further explore the relationship through longitudinal research design. Second, alternative underlie mechanisms can be further investigated since sense of self-determination serves as a partial mediator. Moreover, future studies can explore potential boundary conditions for the relationship between empowering leadership and task performance.