Background and Objectives: Online gaming addiction has a negative effect on the physical and mental health of adolescents. The present study was conducted with the aim of determining the mediating role of cognitive fusion in the relationship between childhood psychological maltreatment and online gaming addiction. Materials and Methods: In the current descriptive study, the statistical population included all middle school students (boys and girls) in the Education Department of Bastak (Hormozgan Province), who were studying in the academic year 2021-2022, and 350 people were selected as a sample using the multi-stage cluster random sampling method. They answered questionnaires of psychological maltreatment, cognitive fusion, and online gaming addiction. Structural equations modeling was used to analyze the data. Results: The results showed that emotional responsiveness, rejection/intimidation, unethical/not being honest, high expectations/inflexibility, and isolation are directly and significantly related to online gaming addiction with coefficient values of 0. 48, 0. 41, 0. 28, 0. 31, and 0. 32, respectively (p<0. 001). Also, emotional responsiveness, rejection/intimidation, high expectations/inflexibility, and isolation have a significant relationship with online game addiction indirectly with the mediation of cognitive fusion with coefficient values of 0. 24, 0. 19, 0. 08 and 0. 14, respectively (p<0. 001). Conclusion: The present study showed that childhood psychological maltreatment has a significant relationship directly and indirectly with the mediation of cognitive fusion, with online gaming addiction. From a practical point of view, experts can evaluate the communication methods of parents with their children on the one hand, and on the other hand, seek to reduce online gaming addiction and cognitive exploits, along with cognitive and retrospective challenges.