The purpose of this study includes: Firstly, to examine the effects of corporate entrepreneurship on market orientation, radical innovation, and organizational performance. Secondly, to examine the mediating effect of the market orientation, radical innovation on the relationship between corporate entrepreneurship and organizational performance. In order to verify the relationships and mediating effect, data were collected from convenient sample of 269 employees at small and medium enterprises in Busan, Ulsan, Gyeongju city to test theoretical model and its hypotheses. All data collected from the survey were analyzed using with SPSS 18.0 and AMOS 18.0. This study reports findings as followed: first, the relationship between the corporate entrepreneurship and the market orientation is positively related. Second, there was also a positive correlation between the corporate entrepreneurship and the radical innovation. Third, there was also a positive correlation between the market orientation and the radical innovation. Fourth, the relationship between the market orientation and the organizational performance is positively related. Fifth, there was also a positive correlation between the corporate entrepreneurship and the organizational performance. Sixth, there was also a positive correlation between the radical innovation and the organizational performance. Finally, the market orientation played as a partial mediator on the relationship between corporate entrepreneurship and radical innovation. The market orientation and radical innovation played as a partial mediator on the relationship between corporate entrepreneurship and organizational performance. Also, the radical innovation played as a partial mediator on the relationship between market orientation and organizational performance. Based on these findings, the limitations of the study and some directions for future studies were presented.