Successful performance in competitive sports requires the integrated coordination of cognitive, psychological, and motor factors, highlighting the need for comprehensive psychophysiological interventions. This study aimed to investigate the effects of heart rate variability biofeedback (HRVB) training on anxiety reduction, cognitive enhancement, and motor performance improvement in competitive shooters. A randomized pretest–posttest trial was conducted with 60 athletes (30 in the HRVB group and 30 in the control group. The experimental group underwent ten HRVB sessions, while the control group received no intervention. Anxiety levels were assessed using the Beck Anxiety Inventory, cognitive function was measured through Flanker attention and inhibitory control tasks, and shooting performance was evaluated via standardized protocols. Data were analyzed using ANCOVA and independent samples t-tests. Results demonstrated a significant reduction in anxiety (p < 0.01), alongside marked improvements in cognitive parameters, including reaction time and inhibitory control (p < 0.05) in the intervention group compared to controls. Furthermore, shooting accuracy significantly increased (p < 0.01). These results indicate the simultaneous impact of HRVB on the psychophysiological regulatory system, which integratively enhances emotional, cognitive, and motor functions. Overall, the findings of this study suggest the potential of HRVB as a comprehensive intervention for improving athletic performance, and future studies should investigate its long-term effects.