The purpose of the study was to determine the effect of physical education games on mathematics achievement of students with intellectual disabilities in Saudi Arabia. The participants of this study was (17) students with intellectual disabilities from inclusive middle school in Riyadh city. In this study, math teacher provided exam of 7 math problems to the participants and calculate the time and correct answers, then physical education (PE) teacher placed the same 7 math problems at the school field and taught these to the participants through activities and games for four weeks. Results indicated that the time and correct answers of students with intellectual disabilities after learning math problem skills through PE classes were significantly improved. The results suggested that PE classes can be one of the efficacious solutions for teaching basic mathematical skills to students with intellectual disabilities. Study recommended the importance of using games in physical education classes to improve the skills of learning in other classes, especially mathematic class.