To evaluate the effectiveness on reducing anxiety of a diaphragmatic breathing relaxation (DBR) training program. This experimental, pre-test-post-test randomized controlled trial with repeated measures collected data using the Beck Anxiety Inventory and biofeedback tests for skin conductivity, peripheral blood flow, heart rate, and breathing rate. The experimental group achieved significant reductions in Beck Anxiety Inventory scores (p < .05), peripheral temperature (p = .026), heart rate (p = .005), and breathing rate (p = .004) over the 8-week training period. The experimental group further achieved a significant reduction in breathing rate (p < .001). The findings provide guidance for providing quality care that effectively reduces the anxiety level of care recipients in clinical and community settings.