This study investigates the effects of side-hustles on career development potential in primary job. Results of multi-source data revealed that side-hustle task complexity can promote role-breadth self-efficacy and inter-role conflict experienced in primary job, which in turn exhibit opposite effects on supervisor-rated promotability in primary job via performance ratings (i.e., task performance and proactivity). Specifically, side-hustle task complexity can increase supervisor-rated promotability by promoting role-breadth self-efficacy experience in primary job and supervisor-rated performance. Meanwhile, it could also hinder supervisor-rated promotability by eliciting inter-role conflict experienced in primary job, which in turn hinder one’s performance ratings. On this basis, we further found that organizational support for strength use in primary job can strengthen the positive effect of side-hustle task complexity on supervisor-rated promotability by intensifying the effect on role-breadth self-efficacy and reducing the effect on inter-role conflict. This study is among the first to examine the effect of side-hustle on career outcomes in primary job, with theoretical and practical implications discussed.
