Karen Jenkins was driving a 1994 Toyota Land Cruiser towards Queenstown, with her daughter, Tamsin, in the passenger seat and their two dogs in the back.
They reached the winding section of the road, known as Twelve Mile Bluff, about 20km from the resort, just before 2pm.
"We were coming around the corner and saw other cars slowing down.
Mum braked [to allow other motorists to pass] and all the rocks came down on the car," Ms Jenkins said.
"We drove through in case there was any more to fall down. We drove further along, but the radiator was leaking and it wouldn't have got [us] much further."
The front passenger door, bonnet and bumper took the brunt of the rockfall.
Both women climbed out through the undamaged driver's door.
Mrs Jenkins called her husband, Philip Jenkins, who called Queenstown police.
Firefighters and ambulance officers did not attend the scene.
Mr Jenkins, who drove his wife and daughter back to town, said he was "very relieved" they were safe.
"We're going to buy a lottery ticket tonight," he said.
Queenstown Lakes District Council roading manager Ian Marshall and Downer EDI Works contractors attended the accident and a digger and truck were used to clear the debris from the road, which was reopened at 3pm.
The Land Cruiser was towed away.
Mr Marshall said it was lucky there had not been any injuries or fatalities.
The rockfall may have been triggered by the effects of winter, Mr Marshall said.
The council has arranged for a geologist to inspect the rock face on Monday morning, and closed one lane along a 100m section of the road until then.
