Abstract: A device for applying a weatherstrip to a motor vehicle body, and a related method. The body bears an elongated receiving surface with a predetermined profile. The application device includes a plate for applying the weatherstrip on the receiving surface, a presser pressing the weatherstrip on the receiving surface, and a guide for guiding the application plate on a trajectory along the predetermined profile of the receiving surface The guide includes a programmable articulated mechanical element for moving the application plate, and that is programmable to adapt the trajectory of the application plate to different predetermined profiles corresponding to different vehicles.