The fire broke out in a plastic and clutch-plate wire manufacturing factory at Narela industrial area at 6 AM, fire department officials said.
Twenty-seven fire tenders were rushed to the spot and the flames were doused by 8.10 AM.
A charred body of an old man, presumed to be a worker, had been found and handed over to police, said a Delhi Fire Service official.
The deceased was yet to be identified.
The cause of the fire is still not known and the matter is being probed.