The present study was conducted with the aim of investigating mindfulness with competitive aggression mediated by tolerance of failure in football players. The research method of this research was descriptive correlation type based on structural equation modeling method. Its statistical population included all the professional football players of Mazandaran province league who were employed there in 2024. To determine the sample size, according to the number of observed variables and assigning a coefficient of 20 for each variable and taking into account the possibility of incomplete questionnaires, 280 people were selected as the sample size using available sampling method. And they answered Drutman et al.'s Mindfulness (2018), Harrington's Failure tolerance (2005) and Maxwell & Morris's Competitive Aggression (2007) questionnaires. Structural regression equation modeling and SPSS and Amos software were used for data analysis. The findings showed that there are significant relationships between mindfulness and competitive aggression mediated by failure tolerance in football players. The variables of mindfulness and failure tolerance have a significant direct effect on competitive aggression, and mindfulness with the mediation of failure tolerance has a significant indirect effect on competitive aggression. It is concluded that the research model was confirmed and in general, 38% of competitive aggression can be explained by mindfulness and failure tolerance.