In geotechnical engineering, rockbolts represent a fundamental component for reinforcing rock masses and enhancing excavation stability. To address the complex mechanical behavior at the anchorage interface, a novel bond-slip model is established that introduces a residual strength coefficient (ξ), enabling a more accurate characterization of the nonlinear bond-slip response in the rockbolting system. The introduced coefficient ξ serves as a key tuning parameter, enabling the model to adaptively characterize a spectrum of bond-slip behaviors, from pronounced softening to marked hardening, which underscores its versatility for application to different interface types. All model parameters were calibrated through laboratory tests, field observations, and inverse analysis methods. The model’s theoretical results, which account for interfacial residual shear stress, show strong agreement with both laboratory and field pullout tests. For 0 < ξ < 1, the rockbolt load-displacement curve exhibits five stages, with ξ significantly influencing anchorage performance, particularly in the elastic-plastic stage compared to the elastic stage. As ξ increases, the anchorage interface transitions from shear softening to hardening. The full process of axial force and shear stress transfer with varying ξ, peak shear strength, initial shear stiffness, and embedment length was analyzed, offering a theoretical basis for understanding load-transfer behavior in rockbolts. Maximum and residual bearing capacities increase with ξ, peak shear strength, and embedment length, whereas initial stiffness negatively affects only the maximum bearing capacity. These findings offer valuable insights for optimizing rockbolts’ design to enhance rock stability.