Josh Fletcher (18), from the Moira area of Co Down, died in the early hours of Sunday after his car left the road after colliding with the animal.
The incident took place on the Moira Road in Lisburn at around 3am.
Sergeant Jonny Mackenzie has appealed for any potential witnesses to come forward.
“Josh was the driver of a car which left the road after colliding with a cow at around 3am on Sunday morning and sadly died at the scene as a result of his injuries,” he said.
“We are currently conducting a number of follow-up enquiries into the collision and the road remains closed at this time with diversions in place.
“Josh was travelling in the direction of Moira, between the junctions with the Bushfield Road and the Moyrusk Road when the collision took place, and I would ask anyone who travelled along this stretch of road in the time leading up to the collision to contact police with any information or dash-cam footage they may have.
“Please call on 101 quoting reference number 227 18/10/20.”
