Shayne Dawe, 46, says he saw three lights converge at around 3am in the national park before the orb "focused a beam of light onto the ground" in the distance.
See also: Strange light appears in Somerset sky
The "jerky and erratic" movements prompted Shayne to whip out his camera at first and capture the sighting - but the lights quickly made him feel ill.
He exclusively told Mirror Online: "When I first saw it it looked like a triangle shape – with the three lights.
The orb of light captured on camera by Shayne Dawe
"Then it converged into one and it seemed to focus a beam of light onto the ground.
"I had to pat myself on my chest just to calm down. The next minute it came right up to me and I realised that I had to get out of there.
"It made me feel nauseous and sick – I never get sea sick or anything like that.
"At that point it was about 200 yards away from me."
The "jerky and erratic" movements prompted Shayne to whip out his camera at first
The lorry driver, from Plymouth, has made visits to Dartmoor for 25 years.
He described how he had been staying in his car for the last two weeks after breaking up with his girlfriend.
After feeling nauseous, Shayne quickly fled the scene and drove to nearby Princetown village.
"It made me fear for my life," he said.
"It was terrifying. When I got to Princetown I thought about calling the police or going to [HMP Dartmoor] prison just for sanctuary."
Dartmoor National Park
In the end, Shayne decided to drive to Plymouth where he stayed at his mum's house.
He added: "When I got on the road to Plymouth I looked in my mirror and saw the object behind me.
"It felt like this thing was stalking me."