Police are investigating after the blaze at La Tana restaurant in Patcham early this morning.
The fire broke out at about 12.30am and caused severe damage to the restaurant as they were expecting a busy day of Father's Day bookings.
Sussex Police said in a statement: "Police are appealing for witnesses following a fire at a restaurant in Patcham.
"The incident occurred at La Tana in Ladies Mile Road at about 12.30am on Sunday (June 18).
"No one was present in the property at the time, however the occupants of the flat above the restaurant were evacuated as a precaution.
The cause of the fire is unexplained at this stage, and police are appealing for anyone with any information to report it online at: sussex.police.uk/appealresponse or call 101, quoting serial 50 of June 18.