The female on-duty officer driving was unhurt.
The road was closed in both directions at the crash site for a police investigation.
Police said Mr Meiklejohn was travelling on the northbound carriageway towards Thurso and his car lost control while overtaking a green Vauxhall Vectra.
A white Ford Transit van travelling out of Thurso took evasive action before the Fiesta collided with the unmarked police car. The female officer assisted at the scene.
A fifth vehicle was struck by debris from the collision.
Sgt Donnie MacKinnon, from the Road Policing Unit, said: “Tragically this collision has resulted in the driver of the Fiesta sustaining fatal injuries and we are currently trying to establish the full circumstances surrounding this incident.
“Anyone who was on the A9 just outside Thurso at around 7pm on Thursday evening and witnessed what happened should contact police immediately.”