The deformation failure modes of gravity retaining walls include overturning, toppling, deep sliding, and eccentric failure. The complex eccentric failure mode, which involves the multi-stage deformation of retaining walls, suffers from a lack of mechanical models and design theories. Based on the basic theory of reinforced concrete construction, this study established a deformation calculation model of bottom-confined reinforced concrete gravity retaining walls (RC-GRWs), which are composed of tensile, compressive, and rigid zones. Then, this study defined RC-GRWs’ normal-operation, cracking, yield, and ultimate limit states, as well as the displacement of RC-GRWs in these states, according to the concrete cracking and steel reinforcement yield conditions. Accordingly, this study proposed a design method and process to determine the deformation of bottom-confined RC-GRWs. A project case shows that the calculation method for RC-GRW deformation proposed in this study can effectively assess the deformation state of in-service retaining walls and that optimized cracked retaining walls can meet the deformation-based design requirements.