Humberside Police today issued an appeal for information on the man and his accomplice after they targeted the Betfred shop in Bilton.
A spokesman said: "One of the men allegedly walked into the shop on Ganstead Lane around 7.30pm on October 31 with a bladed weapon and demanded money. The other man waited outside.
"Staff inside the bookmakers set off the panic alarm and the man ran out of the premises without any money. Both men then ran off in the direction of Ganstead."
The man who entered the shop has been described as white, in his early 30s and about 6ft, with a gaunt looking face.
He was wearing a dark blue tracksuit top with the hood up.
Officers want to speak to anyone who witnesses the incident or who recognises the description of the would-be robber.
Call 101, quoting reference 16/54904/17, or Crimestoppers anonymously on 0800 555 111.