Bentley man Damon Housley captured the footage at the car park on Friars Gate in the town centre.
He said he stopped counting at 20 rats, some 'the size of cats', who weren't fazed by his presence.
"They weren't even bothered by having a human there," he said.
Mr Housley can be heard commentating as he films the rats scurrying about.
"Donny town centre for you," he said.
"There's about 20 of them.
"Dirty Doncaster. Look at them."
His post on Facebook had been viewed more than 2,000 times.
Mr Housley said he was worried about the disease the rats were carrying.
"People walk through the car park, get into their car before walking into their house, stepping on the carpet and bringing diseases into their own homes," he said.
"We pay our council taxes for rubbish to be removed and to keep the town clean, and that's obviously not happening."
His children, three-year-old Rae and Ivy, two, wanted to return to the car park to 'see the animals'.
Mr Housley said he was 'disgusted' with the sight.
"I'm 37, and I've never seen so many rats," he said.