Sussex Police said the incident happened at around 2.30am on Wednesday, August 23 at the Canada Grove junction with Queensway.
A spokesperson for the force said: “A 27-year-old man from Bognor was assaulted and had cash, his watch and ring taken.
“Officers are investigating and any witnesses or anyone with relevant CCTV or mobile phone footage is asked to come forward.”
Anyone with information can report it online or by calling 101, quoting serial 133 of 23/08.
1. Bognor man, 27, assaulted in robbery as police appeal for witnesses
Police are appealing for witnesses to a robbery in Bognor. Photo: Police