Ash Hammond from Durrington in Worthing, West Sussex, spotted the large rodent running through his garden over the course of three days, and it was scaring his children.
He was quoted £70 for an exterminator, so after a sighting in his neighbour's garden, they decided to team up and catch it.
They were both pulling up their decking to look for a nest when the beast was disturbed next door, darting into Ash's garden.
He said: "Because I've repaired all the holes he has made recently he had nowhere to go so we managed to get him with a spade.
"I had a little bit of time to realise what I was up against but I genuinely could not believe my eyes when we finally got it.
"The kids are still talking about it and my neighbours are still burning their decking because they literally cut it to pieces."
Ash said the rat's body was as big as a size 10 shoe and 2ft in total, making it the size of a small cat.
He said: "All the kids cheered because now they can play in the garden again."
After posting pictures of the supersized creature on Facebook, Ash said he had received some negative comments for killing it.
But he added: "We felt relieved and exhausted; after nearly 10 hours of hard work it payed off.
"Some people are not so welcoming with what I've done but we've got a vermin creature out of the garden and that makes us all happy."