In today’s rapidly changing social and employment environment, young university students face unprecedented career development challenges. They must not only acquire strong professional knowledge and skills but also navigate the complex job market. Career calling, as a profound professional value, provides individuals with a clear sense of purpose, laying a solid foundation for their career development. Therefore, cultivating career calling has gained increasing attention in higher education, which is essential for developing future social workers who are both responsible and purposeful. This study aims to reveal the impact of individuals’ career exploration on career calling and its underlying mechanisms, as well as the influence of personality differences during the exploration process. The study was conducted in two universities in Guangdong Province, China, using online questionnaires that yielded 421 valid responses. The results confirmed that career exploration positively influenced career calling, with career decision-making self-efficacy mediating this relationship. Additionally, openness to experience moderates the connection between career exploration and career calling. These findings offer valuable insights for educators and career counselors, helping them develop effective strategies and interventions to support university students in finding and realizing their career calling.