At around 18:00 the 19-year-old was approached by a man on Manners View, who struck up a conversation with the victim and a second man approached who also started talking to him. The victim was punched to the floor and the assault continued.
The area is known as West Bank for the duration of the Isle of Wight Festival and is well used during this time but is not part of the event itself.
The victim suffered reddening to his neck. His wallet containing £200 was stolen.
A 16-year-old has been arrested on suspicion of robbery and bailed until 17th July pending further enquiries.
Anyone who witnessed the offence or has information about it are asked to contact Police on 101.