Numerous empirical studies have examined work- or career-related outcomes in cross-cultural work settings, leading to an emerging research stream in the current literature. Building upon self-determination theory, this study aimed to examine whether protean career attitude is positively associated with subjective career success. We further explored the mediating role of overseas work adjustment and the three-way moderation of cultural intelligence and learning-goal orientation to strengthen this indirect relationship. The data from two studies, encompassing non-Asian (n = 289) and Asian (n = 192) participants, provide convergent support. Statistic procedures, such as hierarchical regression and bootstrapping analysis based on Hayes’ PROCESS on SPSS 28, were conducted to test the hypotheses. The result showed the indirect effect of protean career attitudes on subjective career success through overseas work adjustment. Moreover, this indirect effect is strengthened when self-initiated expatriates only possess higher levels of cultural intelligence and learning goal orientation. Our study contributes significantly to the existing literature by shedding light on the factors influencing subjective career success among self-initiated expatriates in diverse work environments. Our findings also hold practical implications for individuals seeking to pursue protean careers in overseas settings.