<p>The dynamic constitutive behavior of rocks is critical for understanding and mitigating dynamic hazards in deep rock engineering. Deep rock masses are commonly subjected to high in situ stress and rapid stress disturbance, making their mechanical response strongly dependent on the coupled effects of confining pressure and strain rate. However, existing statistical damage constitutive models still have limitations in describing this coupling effect and the full-stage stress–strain response of rocks. In this study, systematic dynamic triaxial compression tests were conducted on granite to investigate the evolution of mechanical behavior under different confining pressures and strain rates. Within the framework of statistical damage theory, a dynamic damage constitutive model was developed by incorporating the confining pressure–strain rate coupling effect, initial crack closure, and residual strength evolution, enabling full-stage prediction under different loading conditions. Results show that granite peak strength is highly sensitive to the interaction between confining pressure and strain rate. Compared with models treating these two effects independently, the coupled-strength model reduces prediction errors by 52%. The crack closure stress ratio and damage stress ratio both decrease linearly with increasing confining pressure. Crack closure strain decreases linearly, peak strain increases linearly, and elastic modulus shows nonlinear growth with increasing confining pressure. The proposed model was validated using multiple triaxial compression datasets and is applicable for confining pressures of 0–225&#xa0;MPa and strain rates of 10⁻¹–10³&#xa0;s⁻¹. This study provides a reliable framework for predicting full-stage rock behavior under coupled confining pressure and strain rate conditions.</p>