A necropsy confirmed the female's death was caused by trauma consistent with being hit by a vehicle.
The kiwi, named Monte Carlo, had been hatched and raised in captivity before being released back into the Okarito sanctuary in 2014, and at four years old was just coming up to breeding age, the Department of Conservation said.
An estimated 450 rowi - or Okarito brown kiwi - are left.
Biodiversity ranger Stacey Lockie said kiwi had no road sense and had been known to dart in front of vehicles at the last minute.
"Kiwi living near the road will often have territories that include areas on both sides of the road, so they will routinely cross the road to access the entire area.
''These kiwi are really rare, so look out for the kiwi road signs and take a bit of extra care driving along this road to keep our rowi safe," Mr Lockie said.
