Background: Decreased muscle flexibility and altered joint mechanics are connected to the onset and progression of osteoarthritis in the knee. The hamstring muscles tend to shorten and contract, which increases the tibiofemoral joint compressive force. Particularly for the hamstrings, stretches and percussive massage might help lessen the limitation of knee extension that is seen in patients with tibiofemoral osteoarthritis or patellofemoral pain syndrome. Purpose: to examine how utilizing a percussion massage gun affects people with knee osteoarthritis' hamstring flexibility, discomfort, range of motion, and function. Methods: 42 patients, ranging in age from 45 to 60 years, of both genders with mild to moderate knee OA were split into two groups of twenty-one patients each at random. Group A, or the control group, received standard physical therapy care involving strengthening and stretching the muscles in the lower limbs for four weeks, three workouts a week. Group B (the experimental group) received the same exercise as Group A in addition to a percussion massage gun on the hamstrings for five minutes, three sessions per week for four weeks. The sit-and Reach test was used to assess hamstring flexibility, the VAS for pain, active knee extension for knee extension ROM, and the WOMAC questionnaire to assess knee joint function. Results: There was a significant improvement (P<0.05) in hamstring flexibility, pain, ROM, and function in group B compared to group A. Conclusions: Percussion massage guns may have a significant effect on improving hamstring flexibility, pain, ROM, and function. This may benefit patients in improving their complaints, and this may benefit physiotherapists as well in improving their practice, as it is simple, easy, effortless, and more effective compared to stretching, especially in cases where knee extension is not recommended.