A driver assistance system, a method for controlling the same, and a radar device are disclosed. The driver assistance system includes a first radar sensor, a second radar sensor, and at least one human machine interface (HMI). The first radar sensor monitors a first rear-lateral sense region, and acquires first radar data from the first rear-lateral sense region. The second radar sensor monitors a second rear-lateral sense region, acquires second radar data from the second rear-lateral sense region, receives the first radar data from the first radar sensor through Direct communication, and identifies an object based on the first radar data or the second radar data. The human machine interface (HMI) displays a warning control signal through in-vehicle communication when the second radar sensor performs warning decision.