Transformational leadership has been shown to impact a wide range of outcomes in sport. Previously, researchers have begun to examine the mechanisms by which transformational leadership exerts its impact on followers. However, there is still little known about the mediating variables between transformational leadership and followers' performance. Therefore, the aim of the current study was to examine the relationship between transformational leadership and the leader-inspired extra effort with the potential mediating role of the coach-athlete relationship in college basketball players. The differentiated transformational leadership inventory (DTLI) was used to assess college coaches' leadership behaviours and the coach-athlete relationship questionnaire (CART-Q) was used to examine the athletes' perceptions of the relationship with their current coach. Accordingly, the leader-inspired extra effort scale (LIEE) was used to investigate the college basketball players' perception of their effort. The sample comprised 78 college basketball players (43 men, 35 women; M[subscript age] = 21.60, SD = 3.05). Results did not provide support for full mediation except the direct effects between individual consideration and leader-inspired extra effort had a significant relationship (ß = 0.491; SE = 0.143, p < 0.01) as well as the individual consideration and the closeness (ß = 0.069; SE = 0.101, p < 0.01). The results highlight that coaches and educators should endeavour to display transformational leadership behaviours as they are related to coach and athlete relationship on the athletic effort.