In this study, three prefabricated integral shear wall specimens with strength differences were constructed based on a real engineering project to investigate the impact of these strength disparities on the structural performance of shear walls. The results indicate that all three prefabricated integral shear wall specimens with strength differences between precast (PC) and cast-in-place (CIP) concrete exhibited bending-shear failure. Moreover, the experimental axial-bearing capacity of the specimens was higher than the calculated axial-bearing capacity obtained using the reduced concrete strength according to the shear wall calculation formula in the code. The ultimate displacement angles of all three specimens exceeded the limit elastic–plastic displacement angle specified for shear wall structures under large seismic motions in the code, and the ductility factors were greater than 3. Furthermore, this paper presents a calculation formula for the axial-bearing capacity of the plane section of prefabricated integral shear walls with strength differences and compares it with experimental results. This paper presents a calculation formula for the axial-bearing capacity of the plane section of prefabricated integral shear walls with strength variations, compares the calculated results with experimental values, and shows that the relative error between the calculated and experimental values is nearly within 10%, which provides a design basis and reference for engineers in calculating the axial-bearing capacity of such shear walls with strength variations.