PurposeThis study aims to explore how autonomy, competence and relatedness impact work-based learning (WBL) motivation and engagement, contributing to enhanced employability skills. Additionally, it examines whether there are significant differences in these effects between students from STEM and social humanities.Design/methodology/approachThis study employed a correlational design with 284 undergraduate students, collecting cross-sectional data through validated surveys on autonomy, competence, relatedness, WBL and employability skills. The analysis utilized structural equation modeling partial least squares (SEM-PLS) and partial least squares-multi-group analysis (PLS-MGA) to explore WBL's mediating role in the relationship between SDT components and employability skills, with comparisons across different academic faculties.FindingsThe results show that autonomy, competence and relatedness significantly enhance students' employability skills through WBL. WBL serves as a mediator that strengthens student motivation and engagement, with notable differences in the effects between STEM and social humanities students.Practical implicationsHigher education institutions should integrate SDT principles autonomy, competence and relatedness into WBL programs to enhance employability skills. Moreover, these programs should be tailored to accommodate the distinct needs of students from various academic backgrounds, such as STEM and social humanities.Originality/valueThis study establishes a novel connection between self-determination theory (SDT) and the development of employability skills through WBL. It provides new insights into the mediating role of WBL in the relationship between SDT components and employability, highlighting the differential impacts across academic disciplines, particularly between STEM and social-humanities students.