Purpose: Firstly, this study diagnosed professional competence amongst Chinese vocational students within a broad range of the manufacturing sectors; then, the authors examined how different types of P-E fit (job, organisation and vocation) and internship quality jointly shape the newly acquired professional competences of interns. Design/methodology/approach: This study utilised the COMET methodology to conduct a large-scale assessment of professional competence amongst 961 graduates from vocational colleges who had successfully completed internships. Participants actively engaged in the data collection process by responding to questionnaires that sought contextual information concurrently. Findings: The majority of students have attained fundamental functional competencies, indicating their fulfillment of basic requirements. However, there is a tendency to overlook the cultivation of shaping competence. Three types of P-E fit and task characteristics are positively correlated with professional competence. The indirect relationship between P-E fit and professional competence mediated by task characteristics was verified through P-V fit and P-J fit except for P-O fit. Overall, the model explains 39.2% of the variance in professional competence. Originality/value: "How to promote professional competence" has been highlighted as an important topic in vocational education. This paper contributes to identify the characteristics of a quality internship program for vocational colleges and firms. These insights are important in considering a student-centred approach, design internships programmes that better fit their own abilities, needs and vocations, avoiding a one-size-fits-all approach to implement internships and thus, enhance students' professional development.