The underrepresentation of women in science, technology, engineering, and mathematics (STEM) fields limits their development, their career opportunities, and societal progress. This study used social cognitive career theory to explore the relationship between informal STEM learning activities and STEM career intention in female high-school students. Using a mixed-methods approach, we surveyed 58 students participating in school-enterprise collaborative informal STEM activities and then conducted semistructured interviews with 11 randomly selected students. The results revealed a significant positive correlation between the frequency of participation in various informal STEM learning activities and the STEM career intention of the female high-school students. Informal learning experiences significantly positively affected the female students' interest in STEM, self-efficacy, outcome expectations, and fulfillment of social needs, thereby promoting their STEM career intention. This study enhances our understanding of the needs of female students in STEM and offers targeted recommendations for educators and policymakers.