The incident happened late on Sunday morning and triggered an urgent search led by HM Coastguard. Lifeboats from Shoreham and Newhaven were deployed, along with a Coastguard helicopter, a fixed wing aircraft and two nearby vessels.
Sussex Police said officers were notified by the Coastguard at 11.40am that a man had been reported missing after going overboard. A body was later recovered from the water.
The man has been identified and his next of kin have been informed. Police offered their condolences, adding that enquiries into the circumstances of the incident are continuing.
Earlier in the day, HM Coastguard said it had received reports at 10.19am that a person had fallen from a vessel in the area and had launched a full search operation.
No further details have yet been released.
