A tail lamp assembly is provided to include a tail lamp and a tailgate lamp. The tail lamp assembly replaces the original taillights of a vehicle with the tail lamp, which is embedded in the rear side plate of the vehicle, whereas the tailgate lamp is attached to the tailgate of the vehicle. The tail lamp is directly controlled by the vehicle to selectively provide specific warning signals. The tailgate lamp is disposed on a surface of the tailgate, extending from the tail lamp at the position within a certain distance from the tail lamp. A light channel or electric channel is selectively established between the tail lamp and the tailgate lamp to link and synchronize the tailgate lamp with the tail lamp, so that the tailgate lamp provides specific warning signals accordingly.