Those high versus low in narcissism tend to perform better in individual performance settings. However, less is known about narcissists influence in team environments. Narcissists self-centred and entitled disposition may contribute to conflicts within a team, leading to decreased team functioning. Therefore, we investigated how narcissism in teams contributes to team functioning via intragroup conflicts. Couched within Trait Activation Theory (Tett & Burnett, 2003), we explored the interplay between individual and team-level narcissism on cohesion. Across two studies we examined cross-sectional (Study 1, N = 306 from 24 teams) and longitudinal (Study 2, N = 400 from 44 teams) perspectives of the influence of narcissism in sport teams. Participants completed measures of narcissism, perceived narcissistic team composition, intragroup conflict, and cohesion. Multilevel Bayesian conditional indirect effect hybrid modelling allowed us to test the effect of individual narcissism on cohesion via intragroup conflict moderated by perceived narcissistic team composition. Results indicated a conditional negative indirect effect through process conflict (only) on task cohesion in Study 1, and on task and social cohesion in Study 2. Specifically, a negative indirect effect was only present when teammates perceived few narcissists to be on the team. Findings suggest that narcissists undermine team functioning when they are in teams comprising of few similar individuals, this effect was mitigated when they perceive more narcissists in their team. Seemingly, the disruptive effects of narcissism can be attributed to the disagreements regarding roles and responsibilities only when few likeminded individuals are in their team.