A thug with a broken bottle ordered Coral workers to open the safe before he escaped out of the back door with cash.
It happened at the bookmakers in Sheep Street, Bicester, around 4.30pm yesterday and police are hunting the man.
He walked into Coral with a broken bottle, shouted at staff and demanded they open the safe.
The man grabbed a wodge of cash and escaped by the back door of the shop.
A worker suffered a minor cut to his wrist during the robbery.
The offender was white with dark cropped hair and was wearing a white Puffa-style jacket with sleeves and dark trousers.
Anyone with information is asked to call investigating officer detective constable Charlotte Eden on 101.
Alternatively, contact independent charity Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org