Customers of From The Forest, in the Forest Hill area were surprised to see the superstar couple show up to place an order.
The musicians - who have been in the United Kingdom while the rapper tours with Kanye West on their Watch The Throne tour - dined in and were relatively low-key according to onlookers.
A source said: "It was surreal to see them sitting there. They looked like an ordinary couple, but obviously they're not.
"They didn't make a fuss and only had a couple of security guards with them. I think they were in the area for business meetings."
Beyonce recently spent £25million buying her partner a luxury aeroplane.
The singer's Father's Day gift to her husband is capable of taking 15 passengers and includes several features you would find in a house.
Jay-Z is headlining Radio 1's Hackney Weekend tomorrow night (23.06.12) where former White Stripes member Jack White is another headliner, however he is on a different stage.