Officers had launched an investigation after the box was taken from the counter of The Lunch Box, in Yoden Road, Peterlee.
The theft happened during the last few days and police say they were alerted after the box was found nearby at 11am on Sunday.
This morning, Durham Police tweeted a picture of the money inside a transparent evidence bag with the words: "We have got your money back mate!!"
Man in life-threatening condition after 'serious collision' involving car and pedestrian in South Shields
Campaigners rally against Local Plan after farmland in Cleadon earmarked for 156 homes
Appeal to find owner of lost Labrador after dog found near Jarrow Cemetery
Pair set up cannabis farm in town centre flat
South Shields man jailed for terrifying physical and sexual assault on woman in her own home
The force said the arrest came as a result of information from members of the public.
The arrested man is in custody at Peterlee Police Station.