This study investigates the role of knowledge sharing in the development of relationship capabilities, focusing on the interaction between exporting organizations and their foreign partners. Knowledge sharing can be defined as the activities of how to assist communities of people work together, facilitating the exchange of their knowledge, enhancing organizational learning capacity, and increasing their ability to attain individual and organizational goals. Knowledge sharing facilitates the development of innovative ideas, creates new business opportunities through the learning process of knowledge workers, and increases the ability of employees to achieve individual and organizational objectives. The exchange of information and knowledge is crucially important in an export marketing context, as a result of the increasing complexity and volatility of the international business environment and the information asymmetry between exporters and their foreign distributors. Knowledge sharing between the two parties enables exporters to gain a better understanding of local market conditions and develop appropriate products that fit the needs and preferences of end-user customers. In an effort to fill an important gap in the export marketing literature, the present study develops and empirically tests a conceptual model of the organizational factors that stimulate the adoption of an export knowledge sharing behavior, the relationship between export knowledge sharing behavior and export relationship capabilities, and the resulting positive outcomes for exporting organizations. The study develops seven research hypotheses, which are then tested using data collected from a sample of Greek direct exporters by means of an online survey. The key informant in this study is the head of exporting activities (hereafter referred to as export executive). The study employs available guidelines in the literature regarding the collection of high quality data from key informants, questionnaire design, and measure development and validation. The data analysis procedure involves the assessment of the psychometric properties of the measurement scales and the estimation of a structural equation model. Study findings provide support for all seven research hypotheses. More specifically, results indicate that the prevalence of an organizational culture that supports knowledge sharing is an important factor that enhances the adoption of export knowledge sharing behavior by export executives. Similarly, export executives’ attitudes towards knowledge sharing have a positive effect on their knowledge sharing behavior. Organizational culture and export knowledge sharing behavior have a positive influence on an exporting organization’s relationship capabilities. In turn, export relationship capabilities have a significant positive effect on export product advantage and export market performance. Finally, a strong positive relationship is evident between export product advantage and export market performance.