"They were a bit frantic - one of them was just blocking the road," the witness said.
"It was a shock to hear something like this had happened, especially in such a populated area."
They told the man, they didn't have a phone and asked him to call for help at about 8.50am.
Emergency services arrived 10 minutes later. Police are now still at the scene, having cordoned off the area as they investigate the cause of the man's death.
The car driver said there were no obvious signs around his body to indicate what had happened.
The joggers had found a backpack nearby with food in it. They had estimated the man was aged in his 60s, but it was hard to tell, the man said.
"I didn't look too much into it because I was on the phone," he said.
The area is also inhabited by rough sleepers.
A man who sleeps in a tent near the scene said lots of homeless people slept in the bush.
He was questioned by police after the death.
He said he's been living in the bush near the museum for around a year, although had moved to the new spot a week ago.
"Students walk down the tracks here all the time. It ain't nothing to do with me I'll tell you that."
A police spokeswoman said officers were called to Lower Domain Dr at about 8.52am.
She said police were now investigating the cause of the death.
A witness told the Herald there were at least four marked police cars on the scene, with several detectives carrying out inquiries.
Police cordoned off the scene and focused at the end of Lower Domain Dr near Stanley St.
Police were also seen carrying a stretcher down through walking path into wooded area.
A favourite destination on Saturday mornings, Auckland Domain is typically filled with joggers, dog walkers, visitors to the Auckland War Memorial Museum and junior rugby players taking part in matches on the fields.
Tree-lined Lower Domain Dr heads down the park's hill towards the ASB Tennis Arena and the start of the motorway.
Auckland Hospital is also located on the edge of the park.