A method for assisting the braking of an aircraft on a runway comprises the steps implemented automatically, including: before the landing of the aircraft on the runway, receiving the input, by a crew member of the aircraft, of a target braking distance by a man-machine interface associated with a processing unit, the target braking distance corresponding to a distance between a threshold of the runway and a selected exit of the runway; engaging an automatic optimized braking mode of the aircraft making it possible for the aircraft to attain the target speed when it reaches the selected runway exit; and—controlling a braking system of the aircraft, while the aircraft is running on the runway, according to this automatic optimized braking mode.