Drawing on the two-factor model of organizational justice and social exchange theory, this study investigates the mediating roles of procedural and distributive justice in the relationship between work locus of control (WLOC) and leader–member exchange (LMX). Using data collected from two cultural contexts – the United States and South Korea – this research further examines whether culture moderates the indirect relationship between WLOC and LMX through perceived justice. The findings indicate that subordinates with an internal WLOC tend to report higher-quality LMX relationships, and that both procedural and distributive justice partially mediate this relationship. Moderated mediation analyses reveal that the indirect effects of WLOC on LMX via justice perceptions are significantly stronger in the U.S. sample than in the Korean sample. These results contribute to the literature by identifying perceived justice as a key psychological mechanism linking individual traits to relational outcomes at work, and by highlighting how cultural values shape this process.