Background: Innovative techniques for teaching to students with intellectual disabilities are applied across the world, since conventional methods may work less efficaciously for them. In this investigation, an innovative method was applied to teach simple mathematics problems to students with intellectual disability. Objective: The purpose of the study was to determine the effectiveness of physical education (PE) games on mathematics achievements in a sample of students with intellectual disabilities in Riyadh, Kingdom of Saudi Arabia. Method: Participants of this study were 34 students with intellectual disabilities from inclusive middle school in Riyadh city. Participants were randomly recruited and, based on severity of their intellectual disability, allocated to an experimental and a control group. The former studied mathematics in PE classes, whereas the control group studied mathematics in pure mathematics classrooms. Results: Results showed significant improvements in post- versus pre-test in both groups. However, participants in the experimental group reported higher improvements compared to the participants in the control group. Conclusions: The present investigation seems to recommend the importance of using PE games during classes to improve learning skills, especially mathematics ones.