The geological sequestration of CO₂ is recognized as an important approach to achieving the “dual carbon” goals and mitigating the greenhouse effect. The integrity of the wellbore has been identified as a critical factor limiting the effectiveness of CO₂ sequestration. Therefore, an in-depth study was conducted on the issue of CO₂ leakage along the wellbore. Based on the principle of cement interface damage and debonding under coupled fluid-solid interaction conditions, a numerical model of the CO₂ sequestration wellbore has been established. The instantaneous leakage process of supercritical CO₂ along different cementing interfaces has been simulated, revealing the mechanism of cement interface damage, delamination, and leakage driven by hydraulic pressure. The influence of engineering geological factors on interface leakage was analyzed, and several measures to enhance the anti-leakage capacity of wellbore cementing interfaces was proposed. The results indicate that the accumulation of high-pressure fluid at the cement interface leads to a continuous reduction of compressive stress and eventually causes a “compression-tension inversion.” When the tensile stress exceeds the cement interface bonding strength, debonding occurs, forming leakage channels. The anti-leakage capacity of the cement interface is positively correlated with compressive stress. Under equivalent conditions, the cement plug-casing interface is more prone to leakage and is identified as a high-risk location for wellbore leakage. When constructing cement plug barriers within the wellbore, it is recommended to select formation sections with low elastic modulus, high Poisson's ratio, and high in-situ stress, apply cement slurry formulations with high elastic modulus, high Poisson's ratio, and high bonding strength, and emphasize wellbore cleaning prior to cement slurry injection to improve interface bonding quality. The findings of this study provide valuable references for the prevention and control of CO₂ leakage along sequestration wellbores.