"Every time I looked up the line was out the door,” Ms Ní Chorraidh said. "It was like that for a solid five hours”
Seven Coffee announced on social media that it would be “open as normal” ahead of the bank holiday.
However, the Glen Road business had to pull the shutters down early on Monday afternoon after selling out of stock.
“We are having to close early today, as we have sold out of nearly everything,” it posted on social media.
“What a day!!
The cafe was one of only a handful of businesses across Northern Ireland which remained open during the state funeral of the late monarch.
Owner Seainty Ní Chorraidh was “blown away” by the huge level of demand for coffee and food.
"This has been our busiest day since we opened and we have served triple the number of customers that we would on our normal busy days,” she said.
"We would normally be busy on a Sunday as practically nowhere within west Belfast is open but today, with everywhere else closed, we have been bombarded with customers and have been run off our feet.
"We just completely sold out of every little crumb, today has been record breaking for us."
Ms Ní Chorraidh said the lack of competition helped usher in new customers.
“I was talking to one customer who came from Holywood and I’ve no doubt others travelled too,” she said.
"We had our regulars in as usual but there were a lot of faces I have never seen before.
"We are a dog friendly cafe and a lot of dog walkers enjoy a coffee.”
As mourners lined the streets of central London and world leaders took their seats in Westminster Abbey a queue formed outside the west Belfast eatery.
"Every time I looked up the line was out the door,” Ms Ní Chorraidh said.
"It was like that for a solid five hours.”
The deli bar ran out of meat and bread by mid afternoon with the soup and milk supply also drying up before the doors closed at 3.20pm.
The owner is delighted her decision to open on the national holiday paid off.
"I had no intention of closing,” Ms Ní Chorraidh explained.
“I’m not a huge fan of the Royals but I would never put those who are down.
"I respect that people wanted to mark the occasion today, but we are always open – we even open on Christmas Day."
The venue, which faces Milltown Cemetery, even gave out free soup on December 25 last year.
"A lot of people go to the graveyard at Christmas and we thought it would be nice to stay open for them,” Ms Ní Chorraidh said.
“We do it for those who have nowhere to go.
“While we are based in west Belfast and are a community hub, we welcome everybody from all backgrounds.”