The value of mentoring is growing substantially as organizations take a renewed interest in employee development to better survive in the dynamic and competitive market today. In the wake of this renewed interest, this meta-analysis was conducted to quantitatively review the multi-level antecedents (e.g., individual, relational, and structural/organizational) of different kinds of mentoring support (e.g., career, psychosocial, role modeling) in organizational settings and to revisit the theoretical underpinnings of each antecedent. Results indicated some key antecedents of mentoring support at individual (e.g., protégé's proactivity, protégé's learning goal orientation, mentor's transformational leadership), relational (e.g., affect based trust, perceived similarity), and structural/organizational levels (e.g., organizational support for mentoring, supervisory mentoring). Recommendations for future research and organizational practice of mentoring are presented. •Multilevel antecedents of mentoring support were quantitatively reviewed in this meta-analysis.•Protégé's proactivity, learning goal orientation, and mentor's transformational leadership were key antecedents at the individual level.•Affect based trust and perceived similarity were key antecedents at the relational level.•Organizational support and supervisory mentoring were key antecedents at the structural level.