Several meta-analyses have shown that personality is an important predictor of Organizational Citizenship Behavior (OCB). However, these meta-analyses have almost exclusively focused on Big Five personality domains, whereas recent evidence suggests that personality might be captured more accurately by the six HEXACO domains. Here, we provide a comprehensive meta-analysis of all HEXACO domain- and facet-level relations with OCB (k = 21). Extraversion (rho = .347) exhibits the strongest relation with OCB, followed by Conscientiousness (rho = .319), Agreeableness (rho = .217), Honesty-Humility (rho = .208), and Openness to Experience (rho = .195). Emotionality does not correlate with OCB (rho = -.002). The six HEXACO domains explain 8.8% of the variance in OCB, whereas the amount of explained variance increases by 3.4% when using the 24 HEXACO facets (R2 = .122). This discrepancy can be explained by masking effects among the facets of Honesty-Humility and Conscientiousness, and by a cancellation effect among the facets of Emotionality. Theoretical and practical implications as well as limitations and ideas for future research are discussed."