Shear failure in reinforced concrete (RC) structures, characterized by their sudden and brittle nature, often results from inadequate shear reinforcement or degradation due to aging or increased loading demands. To enhance shear capacity, various retrofitting techniques have been developed, with external prestressing bars recognized as an effective solution. These bars apply an active clamping force to improve shear resistance and delay the formation and propagation of diagonal cracks. This review presents a comprehensive analysis of experimental investigations and numerical models, such as strut-and-tie and damage-plasticity approaches, to evaluate shear strengthening with external prestressing bars. In this review, early exploratory studies, the evolution of experimental programs, and the development of analytical and finite element models for predicting the behavior of strengthened beams are examined. Particular attention is given to validating numerical models against experimental data, focusing on load-sharing mechanisms, ductility, failure modes, and serviceability. Practical design implications are evaluated, research gaps are identified, and recommendations for future studies are proposed to advance the implementation of this technique. Findings from authoritative sources are integrated to provide a definitive reference for researchers and engineers seeking sustainable and efficient shear retrofit solutions.