The man, who is believed to be in his 60s, is thought to have been assisting a driver whose vehicle went off the road when the accident happened.
The pensioner was struck by the car on an unclassified road between the A96 and the Chapel of Garioch.
Heavy snow fall was causing chaos in the area at the time with a spate of road accidents and tailbacks.
Paramedics rushed to the scene and took the injured pensioner to hospital in an ambulance for treatment.
The male police driver was uninjured but was said to be suffering from shock.
Six police cars were called to the scene, with 11 officers attending the site of the collision after the accident was reported.
They arrived to find a tractor in front of the police car but police said the farm vehicle was not involved.
Yesterday Grampian Police Chief Inspector Ian Wallace said: "A police car from the Aberdeenshire division with a single male officer was driving on a normal patrol.
"He was not attending any calls. His vehicle struck a pedestrian on the carriageway.
"We understand that pedestrian may have been offering assistance following an earlier collision where we believe a vehicle had gone off the road."
The accident happened during rush hour traffic at about 8:30am yesterday.
Police said the man's injuries were not believed to be life threatening.
Mr Wallace described the officer who was driving at the time as "very shaken".
He was taken to a police station as the accident was investigated.