Despite the benefits of protean career orientation to individuals and organizations in the changing and uncertain working environment, the antecedents of protean career orientation still need to be explored, especially in the non-Western context. In this study, we proposed a moderated mediation model to investigate the predicting factors, including an Eastern value closely related to Easterners’ preference for changing and the future, namely Yin-Yang values, and the protean career orientation development mechanism. Based on a sample of 433 full-time employees from mainland China and Japan, the results showed that Yin-Yang values predict protean career orientation directly and indirectly via career adaptability. Meanwhile, the mediating effect was stronger for individuals with low traditional gender role beliefs and stronger in China rather than Japan. Our findings imply that Eastern values towards change and gender roles may impact the formation mechanism of protean career orientation, suggesting a further discussion and examination from an indigenous perspective.