Purpose: Secondary prevention of coronary artery disease, self-management behavior, and blood pressure control are important to cardiovascular event prevention and promotion of quality of life (QOL), but they are underutilized. The purpose of this study was to investigate the effects of a self-efficacy theory–based health information technology intervention implemented through blood control and patient self-management. Design: A clinical randomized waitlist-controlled trial. Methods: The study was conducted at a medical center in Taipei, Taiwan. A total of 60 subjects were randomly assigned to either the immediate intervention (experimental) group or the waitlist control group. The primary endpoint was systolic blood pressure at 3 months; secondary end points included self-management behavior and QOL. Treatment for the immediate intervention group lasted 3 months, while the waitlist control group received routine care for the first 3 months, at which point they crossed over to the intervention arm and received the same intervention as the experimental group for another 3 months. Both groups were evaluated by questionnaires and physiological measurements at both 3 and 6 months postadmission. The results were analyzed using generalized estimating equations. Results: Systolic blood pressure significantly improved for the intervention group participants at 3 months, when there was also significant improvement in self-management behavior and QOL. There was no significant or appreciable effect of time spent in the waitlist condition, with treatments in the two conditions being similarly effective. Conclusion: The use of a theory-based health information technology treatment compared with usual care resulted in a significant improvement in systolic blood pressure, self-management behavior, and QOL in patients with coronary artery disease. Clinical Relevance: This treatment would be a useful strategy for clinical care of cardiovascular disease patients, improving their disease self-management. It also may help guide further digital health care strategies during the COVID-19 pandemic.