Reinforced concrete (RC) beam–column joints are among the most critical regions in moment-resisting frames subjected to lateral loading, and inadequate joint performance may significantly reduce the strength and ductility of structures. This study investigates the feasibility of using precast high-performance fiber-reinforced cementitious composite (HPFRCC) elements for strengthening RC beam–column joints. First, the mechanical properties of wollastonite-modified HPFRCC were experimentally evaluated through direct tensile, flexural, and compressive tests, and an appropriate mixture was selected for strengthening applications. Subsequently, a finite element model of a 1:3 scaled RC frame was developed in Abaqus and validated using available experimental results.A parametric study was then carried out to evaluate the effects of different strengthening configurations, including side plates (S), L-shaped elements (L), and a combined system ©. In addition, the influence of strengthening length was investigated using the dimensionless parameter α, defined as the ratio of strengthening length to beam depth. The results demonstrated that the proposed HPFRCC strengthening systems significantly improved the load-carrying capacity of the beam–column joint. The side plate, L-shaped, and combined strengthening systems increased the ultimate load capacity by approximately 14%, 32%, and 50%, respectively, compared with the unstrengthened specimen. Moreover, increasing the strengthening length up to α = 1.6 considerably enhanced the structural performance, whereas further increase in strengthening length had a negligible effect on the response. Therefore, α = 1.6 was identified as the strengthening length considering both structural efficiency and economical use of materials