Coaching styles of coaches and team cohesion in sports affect the effectiveness of the team. The main purpose of this study was to examine the relationship among team cohesion, coaching styles, and coaching effectiveness in Amhara league volleyball teams, Ethiopia. The study employed 11 volleyball teams (N = 124) that participated in Amhara league volleyball competition. Therefore, participants were selected by using comprehensive sampling methods so that all volleyball players in the 11 Amhara league teams were samples of the study. Each athlete completed, a Group environment questionnaire, to measure team cohesion, a leadership scale for sport for coaching styles, and a Coaching efficacy scale, to measure the coaching effectiveness of coaches were employed. Descriptive statistics (Mean and standard deviation), Pearson correlation, and multivariate regression analysis were undertaken to analyze and predict which factor predicts coaching effectiveness from team cohesion and coaching styles dimensions at the 5% level of significance. The result showed that training and instruction style was the player’s most perceived coaching style and autocratic style was the least and motivation efficacy was the highest in coaching efficacy subscales. There is a positive and significant relationship found between task cohesion and all coaching styles except autocratic style and social cohesion with all coaching styles except social support style. And team cohesion was negatively correlated with all dimensions of coaching efficacy and there was a positive and significant relationship between training and instruction style with motivation, strategy, and technique efficacy dimensions, positive feedback, and social support styles were correlated with technique efficacy and a Multivariate regression test revealed that training and instruction coaching style positively predicted coaches’ coaching effectiveness.