To reveal the failure mechanism of jointed rock with through-going joints under unloading conditions, the discrete element method was employed to conduct triaxial loading-instantaneous unloading simulations at different joint inclinations and confining pressures. Based on acoustic emission (AE) source parameters and quantitative seismological theory, the spatiotemporal evolution and dynamic development of rock fracturing processes were systematically analyzed, and the controlling effects of joint inclination and confining pressure on rock failure were clarified. The results show that joint inclination and confining pressure jointly determine the distribution and propagation paths of major fracture zones, from which six shear-dominated and one tension-dominated typical failure modes are identified. Despite varying stress conditions, AE responses exhibit similar characteristics, allowing the entire failure process of jointed rock to be divided into three stages: the AE quiet period, the AE growth period, and the AE outbreak period. In the AE outbreak stage, the total number of AE events, the proportion of high-magnitude events, and the released energy increase significantly, driving rapid fracture propagation, coalescence, and structural failure. During the AE growth stage, the b-value decreases with increasing stress level, where b is the slope of G-R relationship fitted line. While in the AE outbreak stage, elevated shear stress, enlarged fracture scales, and clustered AE spatial distributions result in b-values markedly lower than those during the pre-peak loading stage. These findings provide useful insights into the analysis of failure processes and disaster prediction of deep jointed rock masses.