Guided by social cognitive career theory, the current study aims to examine the effect of international students’ personal factors on their career decision self-efficacy (CDSE) in a postsecondary educational context. We also examine the moderating effect of their cultural adjustment on the relationships between their personal factors and CDSE. Data were collected from international undergraduate and graduate students at a large public university in the United States. Structural equation modeling was adopted to test the hypotheses based on analysis from 341 responses. The results indicated that international students’ positive psychological capital positively influences their CDSE. Their cultural adjustment also moderates the effects of psychological capital on CDSE. The results identified critical factors that influence the career development of postsecondary international students, which may help administrators and career counselors understand the unique issues that international students face in their career development and make informed decisions about strategic priorities and interventions.