The collision happened near Gleneagles, Perthshire, at 3.20pm yesterday.
The 79-year-old pedestrian, who has not yet been identified, died as a result of his injuries, police confirmed.
A force spokeswoman said: "Police Scotland along with other emergency services attended at the A9 at Gleneagles after reports of a road traffic collision involving a car and a pedestrian.
"Anyone who may have witnessed the collision is asked to contact Police Scotland on 101."
The southbound carriageway was closed for some time for investigations surrounding the collision to be carried out.