The 28-year-old victim was walking along Gillespie Road in Colinton at around 11.05pm on Tuesday, when the trio of male suspects approached him from behind and hit him on the head.
After falling to the ground, the man was robbed of his belongings before the suspects made off towards Colinton Dell.
Police were called to the scene and the man was taken to the Edinburgh Royal Infirmary where he was treated for cuts to his face.
The suspects are described as white and in their 20s.
A police spokesman said: “The victim suffered painful injuries to his face as he was robbed during this incident.
“We are now eager to hear from anyone who was in or around Gillespie Road at 11.05pm on Tuesday and saw anything suspicious.
“Similarly, anyone with information that can identify the men responsible for this assault is asked to contact police immediately.”