Purpose: To examine the effects of a smartphone application-based exercise program on self-efficacy expectations (SEE) and outcome expectations regarding exercise (OEE), physical fitness, activity level, physiological indices, and health-related quality of life in a sample of hemodialysis patients. Methods: A quasi-experimental control group pre-test post-test design was used. Subjects were recruited from two university hospitals in G city. The subjects were assigned randomly by coin toss: 33 participants to the experimental group and 30 to the control group. A literature review and the self-efficacy theory were used to develop the smartphone program. Experts designed and verified the program to be userfriendly and in consideration of user interaction. Data were collected through a self-report pre-test post-test questionnaire and online medical records. Results: In the experimental group, the levels of physical fitness and physical activity were significantly improved post-test, but the scores on health-related quality of life and the physical indices did not improve. In the experimental group, the SEE and OEE post-test scores were also significantly higher than the pre-test scores, but the control group’s scores did not change. Conclusion: The smartphone application- based exercise program based on self-efficacy theory significantly improved the level of physical fitness and activity, SEE, and OEE for hemodialysis patients. The use of this application-based exercise program for hemodialysis patients might be an effective nursing intervention tool for improving SEE, OEE, level of physical fitness, and physical activity.