Purpose This study investigates how downward envy affects interpersonal conflict, workplace ostracism and displaced aggression in the mentoring context. It seeks to deepen our understanding of how these dynamics influence a mentor–protégé relationship. Design/methodology/approach Employing a three-wave research design, this study uses a sample of 176 participants in mentoring relationships to test our proposed moderated mediation model. Findings Downward envy can increase interpersonal conflict, workplace ostracism and displaced aggression. A mentor’s social comparison orientation moderates these effects by amplifying the negative impacts of downward envy. Research limitations/implications These findings have practical implications for both mentors and protégés. Practical implications These findings have practical implications for both mentors and protégés. Originality/value This study contributes to the literature by focusing on downward envy within the mentoring context, yielding valuable insights to navigate mentoring experiences at work.