Purpose This study aimed to explore the effects of a music-based rhythmic exercise program of upper and lower extremities on lymphedema, muscle strength, and physical function in post-mastectomy. Methods Fourteen women who underwent mastectomy volunteered to participate. All participants underwent a music-based rhythmic exercise program while walking on a treadmill, which consisted of four upper-limb exercises with dumbbells. The intervention was performed for an average of 1 hour, 5 times a week for 8 weeks (a total of 40 sessions). Outcome measures included the extent of lymphedema, shoulder muscle strength, shoulder pain disability index, and a 6-min walk test. Results Outcome measures included the extent of lymphedema, shoulder muscle strength, shoulder pain disability index, and a 6-min walk test. There were significantly improved scores for all the parameters after the intervention (p<0.05). Conclusion This finding suggests that a music-based rhythmic exercise program combined with treadmill walking may favorably improve lymphedema, shoulder muscle strength, shoulder pain and disability, and walking endurance in post-mastectomy women.