Rheumatic diseases are known to be associated with the development of metabolic syndrome, which increases mortality rates due to cardiovascular complications. Although a variety of self-management programs for rheumatic diseases have been developed, few have concentrated on metabolic syndrome. This study aimed to develop and verify a blended (a mixture of telephone and online interventions) metabolic syndrome self-management program. The program was developed in four stages: analysis to identify program contents, website design, website development, and validity testing. A quasi-experimental nonequivalent control group, pretest-posttest design was adopted to verify the program effectiveness in 54 patients with rheumatic disease. The program was initially implemented via telephone for 4 weeks and then self-administered via a web-based platform for 20 weeks. Indices of metabolic syndrome and self-management and quality of life scores were measured as outcome variables. Data were collected three times: before intervention, after 4 weeks of telephone interventions, and after 20 weeks of online self-interventions. The devised program had a significant overall effect on metabolic syndrome indices, metabolic syndrome-related self-management behaviors, and quality of life. Detailed analysis showed the program effectively reduced body mass index, waist circumference, systolic blood pressure, and blood glucose levels and improved metabolic syndrome self-management behaviors. Based on our findings, it can be expected that the use of this program may retard or prevent the progression of metabolic syndrome by improving some metabolic syndrome indices and metabolic syndrome-related self-management behaviors, which are key components of care in rheumatic disease patients with metabolic syndrome. This web-based program appears to be beneficial in public health care settings because it is cost-effective, readily available, and may provide long-term support.