Police have released striking CCTV images of the man who targeted the William Hill shop, in Ring Road, Lower Wortley, at 10.35am on Saturday.
The man pulled the sword from his trousers as he entered the store and shouted threats. A female member of staff behind the counter triggered the alarm and escaped to a backroom while customers ran outside.
The suspect then left empty handed.
He was described as white, aged in his mid-to-late twenties and thin. He was wearing a burgundy Nike hoody, which was spattered with white paint, and had his face masked with white material, which had the appearance of a surgical mask.
Detective Constable Nathalie Tasker, of Leeds District CID, said: “This was a frightening experience for those involved to be confronted by a man armed with a sword. His clothing and the sword itself are quite distinctive items and we would like to hear from anyone who thinks they know who he is.”
Anyone with information is asked to contact DC 2597 Tasker at Elland Road via 101 or call Crimestoppers anonymously on 0800 555 111.