The 58-year-old had picked up his winnings from the Ladbrokes in Main Street, Whitburn, on Tuesday afternoon and was walking into Union Drive at around 6pm when he was grabbed from behind.
Two men pulled him to the floor and stole his wallet, which contained his winnings and bank cards. They then ran off into West Main Street and down an alleyway towards Dean Street.
The first suspect is described as being white, around 18 years old, 5ft 7ins tall, of medium build, with short blond hair with red streaks through it.
The second is described as a white man, around 30 years old, slim and wearing dark clothing.
Lothian and Borders Police are appealing for witnesses to the robbery.
A police spokesman said: “While the victim wasn’t badly injured, he was still shaken as a result of his ordeal, and we are appealing for any information that can help us trace those responsible.
“Anyone who was in the area of Main Street in Whitburn yesterday, who thinks they may have seen the two suspects there, should contact police immediately.
“Similarly, anyone who recognises their descriptions should also get in touch. One of the suspects had distinctive red streaks through his hair, and we are hoping that someone may be able to identify him to us.”
Anyone with any information should contact Lothian and Borders Police on 0131 311 3131, or Crimestoppers on 0800 555 111.