Abstarct: Background and Objective: nutrition is one of the factors influencing sports performance, adaptation to exercise, and athletes’ health. Bodybuilding and fitness coaches, as one of the important sources of nutrition-related information for athletes, may play a significant role in shaping their nutritional behaviors. Therefore, adequate knowledge of sports nutrition among coaches is of particular importance. The present study aimed to assess the level of sports nutrition knowledge among bodybuilding and fitness coaches and to determine its association with selected individual and professional characteristics, including educational level and coaching experience. Methods: This descxriptive cross-sectional study was conducted among 110 bodybuilding coaches in Shahroud city. The required data were collected using a questionnaire, and the coaches’ sports nutrition knowledge was assessed. Spearman’s correlation coefficient was used to examine the relationships between sports nutrition knowledge and age, educational level, and coaching experience, while the Mann–Whitney U test was used to compare knowledge between male and female coaches. In addition, multiple linear regression analysis was performed to identify independent predictors of sports nutrition knowledge. Data were analyzed at a significance level of p < 0.05. Results: The mean sports nutrition knowledge score of the coaches was 16 ± 5.2 out of 35. A significant positive correlation was observed between age and sports nutrition knowledge (r = 0.29, p < 0.05). Educational level (r = 0.36, p < 0.05) and coaching experience (r = 0.26, p < 0.05) were also positively and significantly correlated with sports nutrition knowledge. However, no significant difference in sports nutrition knowledge was observed between male and female coaches (p > 0.05). In the multiple regression analysis, educational level was the only variable that independently predicted sports nutrition knowledge, and the variables included in the model collectively explained 17.9% of the variance in sports nutrition knowledge. Books and scientific articles were the most common sources of nutrition-related information among the coaches, followed by federation educational classes. Conclusion: The findings of the present study indicated that the level of sports nutrition knowledge among bodybuilding coaches was not optimal. Although age, educational level, and coaching experience were positively associated with sports nutrition knowledge in bivariate analyses, educational level was the only independent predictor of sports nutrition knowledge. Furthermore, gender was not significantly associated with the coaches’ nutrition knowledge. Given the role of coaches in providing nutrition-related information and recommendations to athletes, strengthening specialized and evidence-baxsed sports nutrition education for bodybuilding coaches appears to be necessary.