Modular unit structure system has been used increasingly for mid-rise buildings where repetitive units are required. By assembling the pre-made modular unit structures, a building can be easily constructed. The assembled building must behave as one single structure to effectively transfer the forces and moments developed by gravity and lateral loads. For this, individual modular unit structure has to be properly connected to each other. Therefore, evaluation of the connection behavior of modular unit structure system is crucial. This study proposed the embedded steel column-to foundation connection for modular unit structure system and evaluated the behavior of the proposed connection. A series of experiments was performed to investigate the effect of embedment depth of the column, the shape of the end plate, and the shear studs in the embedded region of the column on the connection behavior. Further, advanced three dimensional nonlinear finite element analyses were conducted for each experiment specimen to demonstrate the failure mechanism of the proposed connection in depth. Finally, a design equation for the proposed connection was suggested.