Post-installed rebar (PIR) systems have become an essential solution for the repair, strengthening, and retrofitting of reinforced concrete structures by providing reliable anchorage without extensive structural reconstruction. However, accurately predicting their tensile behavior and failure mechanisms under varying service conditions remains challenging due to the complex interaction among the reinforcing bar, adhesive layer, and surrounding concrete. This study presents a combined experimental and three-dimensional finite element investigation of the tensile behavior of PIR systems using ABAQUS. The numerical model incorporated the Concrete Damaged Plasticity (CDP) model for concrete and an elastoplastic constitutive model for reinforcing steel to simulate nonlinear material behavior and bond degradation. Numerical simulations were conducted for embedment depths of 100, 200, and 300 mm under monotonic pull-out loading and thermal exposure. The numerical predictions were validated against experimental results and demonstrated excellent agreement, with prediction errors below 5% under monotonic loading. The results showed that increasing embedment depth significantly enhanced pull-out resistance, with pull-out loads increasing from 2.426 kN at 100mm to 28.702 kN at 200mm and 74.242 kN at 300mm for experimental and 2.510 kN at 100 mm to 29.133 kN at 200 mm and 73.510 kN at 300 mm for numerical under monotonic loading. Thermal exposure reduced bond integrity and promoted premature pull-out failure. Overall, the validated finite element model reliably predicted the structural response of PIR systems and provides an effective tool for evaluating bond behavior, optimizing anchorage design, and improving the safety, durability, and performance of reinforced concrete retrofitting systems.