The incident happened yesterday afternoon when the man brandished a knife in the Greggs shop in Lauchope Street, Chapelhall, Lanarkshire.
Shocked staff handed over a three-figure sum of money and the suspect ran off on foot.
No-one was injured but the two female staff members were said to be "very distressed by their ordeal".
Police Scotland detective constable Nicola Byrne said: "I would appeal to anyone who saw the suspect either before or after the robbery to come forward. Lauchope Street is the main street through Chapelhall and may well have been busy with pedestrians and motorists at the time.
"Chapelhall is a close knit community and locals will be disgusted that this has happened to one of their own."
The suspect is described as a white male, around 5ft 8in, with a local accent and aged between 20 and 30. He was wearing a black beanie type hat, black woollen gloves and had a black scarf covering some of his face.
Anyone with information is asked to telephone the CID at Coatbridge on the non-emergency number 101 or Crimestoppers on 0800 555 111.
Meanwhile, police are appealing for witnesses after an attempted robbery at Poundland in Anniesland, Glasgow.
At around 6.15pm last night, a man entered the store in Great Western Road and threatened a 19-year-old female member of staff with a knife.
He demanded cash but she was unable to open the till and he fled empty handed.
The suspect is described as a white male, aged 20 to 25 and between 5ft 5in and 5ft 8in. He had short, cropped blond hair with a scar on his left cheek. He was wearing a light blue hooded jacket, dark jeans and white trainers.