Archaeologists found the adult male – aged between 25 and 35 when he died – with fatal cut marks to his neck as they carried out a dig for Rampion Offshore Wind Farm.
Other than a few small bones missing from the hands and feet, the skeleton was recovered completely intact from the ancient route of the South Downs Way – an area known for prehistoric graves.
There was no sign of a coffin, with the remains laid facing upwards with his arms by his side.
Archaeology South East project manager Jim Stevenson, said: “Specialist osteological assessment and radiocarbon dating has revealed that the skeleton is most likely to be an execution burial of the later Anglo Saxon period of around 1010 to 1025 AD.
“Most significantly, two cut marks made by a sharp blade or knife were found at the mid-length of the neck, which would have proved fatal for the individual.”
The wind farm commissioned the dig as part of surveying work for onshore cabling on the South Downs at Truleigh Hill, which is north of Shoreham-by-Sea.
It is hoped that the farm, which is eight miles (13km) off the Sussex coast, will be fully operational later before the end of 2018 and provide enough electricity to supply almost 347,000 homes a year.