Surveillance cameras recorded the men entering Betfred in Cooden Sea Road, Little Common, in the east of the county, wearing masks and threatening a member of staff with what appears to be handguns.
One of the men approached the shop counter, leapt over it and took the contents of the till before both men escaped.
The suspects were both about 5ft 10in to 6ft and were wearing hooded tops and masks over their faces.
On leaving the shop they ran off along the A259 in the direction of Hastings. They are believed to have escaped in a red Ford Fiesta.
The robbery happened at 8.45pm on Wednesday November 5 but officers have so far been unable to identify the men involved. It is not currently being linked to any other incidents.
Detective Constable Paul Wren said: “So far we have been unable to identify the robbers but we are determined we will find them.
“We need to speak to anyone who saw the men going into or leaving the shop or who may have heard who was responsible.
“The robbers may have boasted to someone about what they did so there could be members of the community who know who was responsible. I would urge anyone who hears anything to contact us immediately.”
Anyone with information should email [email protected] quoting Operation Bembrook, call 101 or contact the independent charity Crimestoppers anonymously on 0800 555111.