Increased globalization of sales activities, differences of customer needs, and intensive competitiveness are creating high degrees of environmental uncertainty in the export markets. Under these circumstances, it is very important to recognize firms must sense various market changes and respond to them for attaining competitive advantages and sustainable growth. When firms are involved in worldwide operations, these capabilities will be very critical and valuable for their success. According to many previous researchers, market orientation leads to accumulation of these competencies and it will provide naturally superior export performance. Even though the benefits of market orientation have been recognized for several years, empirical studies have not been conducted enough. This study tries to examine the impact of market orientation on export performance via the competitive advantages which are market sensing and responding capabilities. To achieve this purpose, the authors reviewed the previous literatures and suggested the empirical link among market orientation, market sensing capability, market responding capability, and export performance as well as the determinants of market orientation. After the review of extant studies, the authors designed a research model and proposed ten hypotheses. Based on the collected 274 Korean export firms’ data, the proposed model was testified with the LISREL 8.30. In result of empirical test, seven out of ten hypotheses were supported. According to the empirical results, even though Korean export firms can get superior performance by increasing the degree of market orientation, we need to evaluate the importance of the mediating role of market sensing and responding capabilities between market orientation and export performance. That is, researchers should take a consideration that market orientation’s effect on performance is positive when mediated by market sensing and responding capabilities. In the view of practical implication, Korean export firms should enhance the level of sensing and responding competencies which resultantly ensure superior export performance. The strong positive relationships of learning orientation, entrepreneurship, and competitive intensity on market orientation are also empirically supported. The authors discussed the meaning of the results and suggested future research directions.