This study aims to determine the improvement of shot put learning using the O'Brien technique through modified tennis balls at SMAIT Al Mumtaz Pontianak. The research employed a classroom action research design with a quantitative approach. The subjects of this study were 13 students from class X of SMAIT Al Mumtaz Pontianak. Data collection was carried out using a motor skill test. The results of this study indicate that the application of modified tennis balls in teaching the O'Brien style shot put was highly effective. In the first cycle, only 5 out of 13 students (38.47%) achieved mastery, while in the second cycle, 11 out of 13 students (84.62%) achieved mastery, showing a significant improvement of 46.15%. These findings suggest that the use of modified tennis balls can enhance students’ understanding and execution of shotput techniques, making the learning process more engaging and effective. Therefore, it can be concluded that this learning modification is a valuable strategy in physical education.