This study examines the effects of follower–leader congruence in collectivism on in-role performance, with leader–member exchange (LMX) as a mediating mechanism and perceived inter-team competition as a boundary condition. Based on person–environment fit and similarity–attraction theories, it hypothesizes that collectivism congruence enhances LMX, thereby improving performance. Data were collected from 307 employees (256 followers and 51 leaders) in a Chinese energy company. Results show that congruence in collectivism between followers and leaders enhances LMX quality, which positively influences in-role performance. Moreover, perceived inter-team competition moderates the indirect relationship between collectivism congruence and performance via LMX. These findings extend the person–supervisor fit literature by clarifying the mechanism linking value congruence to performance and emphasizing contextual influences.