The raider struck shortly after the member of staff opened Morrisons Daily convenience store on King Edwards Drive in Bilton, Harrogate, yesterday morning.
Police say the robber grabbed two trays of vapes when he went into the shop.
The shopworker confronted him but the robber punched him in the face and threatened more violence before making his escape with the vapes
Police are appealing for information about a man with a rucksack in the streets around the shop about the time of the robbery.
A spokesman said: “We are appealing to anyone who was in the area at the time and saw a man with a rucksack in the streets surrounding the store, either before or after the incident, to get in touch.
We are also appealing to anyone who may have recorded the suspect on CCTV, doorbell video camera or dashcam if they were driving past at the time.”
Anyone with any information is asked to email harley.wilkinson2@northyorkshire.police.uk or call 101 and pass information to Harrogate CID.
If you wish to remain anonymous, you can pass information to Crimestoppers on 0800 555 111.
Please quote reference number 12250010366 when calling.
