A spokesperson for Sussex Police said: “Police were called to the scene in Upperton Road to assist emergency service partners about 12.20am on Sunday, April 13.”
Residents were told to avoid the area while crews from East Sussex Fire and Rescue were tackling the fire.
The blaze was put out at approximately 7.12am.
Police said the fire was extinguished and the sole occupant of the flat – believed to be a man in his 70s – was pronounced deceased.
A spokesperson for Sussex Police added: “His next of kin have been informed and supported by specialist officers.
“A number of occupants from neighbourhood flats were safely evacuated and have been relocated at alternative accommodation with the assistance of the local authority.
“The public can expect to see a police presence in the area as the cause of the fire remains under investigation.
“Anyone with any information is asked to report it online or call 101, quoting Operation Maverick.”

1. Man dies following fire at Eastbourne flat
Man dies following fire at Eastbourne flat Photo: Sussex news and Pictures

2. Man dies following fire at Eastbourne flat
Man dies following fire at Eastbourne flat Photo: Sussex News and Pictures

3. Man dies following fire at Eastbourne flat
Man dies following fire at Eastbourne flat Photo: Sussex News and Pictures

4. Man dies following fire at Eastbourne flat
Man dies following fire at Eastbourne flat Photo: Sussex News and Pictures