The customer – who has not been named – spotted the vermin in the car park of the McDonald’s store in Greenhithe, Kent.
In the clip, the man records one of the rats appearing from behind a building.
Another “comes out to play” while a third is spotted behind some trees.
He then directs the camera to a bin shed, where he claims the rats are coming from.
“Look, look, loooooook, wow, look,” the man says.
“Big f*****s mate.
“I’ve never seen this many rats in my life.”
Speaking after the incident, he said: “After a hard day at work I fancied a cheeseburger from McDonald’s so stopped off at the nearest one off of the A2.
“I pulled in, found a parking space as you do before going in and ordering, looked out of my car window and saw a rat.
“I was shocked, it took me by surprise, it was huge.
“I looked again and saw two or three and as I continued to look in total shock I noticed to the right of my car that there were rats climbing all over the trees, running through the car park.
“Safe to say I didn’t fancy that cheeseburger anymore.”
A McDonald’s spokesman confirmed pest control experts had been called to the site to assess the situation.
“Consultation is ongoing and we will follow their recommendations to address the problem,” they said.
“This issue does not in any way affect the inside of the restaurant, which has a five-star Food Hygiene rating.”