<p>A recently developed anchorage technique, known as tension–compression composite anchor (TCCA), has gained significant attention from geotechnical engineers. In comparison with tension anchors and compression anchors, TCCA offers superior bearing performance and relatively convenient construction process. This study aims to investigate the load-transfer behaviors of TCCA through theoretical modeling. As a starting step, a novel adhesion–friction-based composite exponential (AFCE) interface model was developed to describe the soil–anchor interface nonlinear mechanical behavior. The parameters of the AFCE interface model can be identified through the utilization of interface shear characteristic values. Despite comprising only three parameters, this model effectively characterizes both the interface softening and hardening behaviors while also accounting for the influence of normal stress. The excellent match between the predicted and measured interface shear stress–displacement curves examined the effectiveness of the AFCE interface model. A generalized load-transfer theoretical framework for TCCA was proposed by integrating the AFCE interface model. Finite element models were established for tension anchor, compression anchor, and TCCA. A detailed analysis was conducted on the bearing capacities and stress distributions for all three types of anchors. The predicted pullout responses agree well with the results from FE simulations as well as from in–situ and laboratory model tests for each type of anchor, proving the extensive applicability of this theoretical framework. Parametric studies were finally conducted to investigate the effect of some key parameters on the bearing capacity of TCCA.</p>