Firefighters were called to the fire at 2:30am, after the control room received a number of calls reporting flames in the restaurant building on Marine Parade.
On arrival, crews confirmed that there was a fire on both the ground floor and first floor (100% alight) and the roof was also affected (50% alight).
Multiple firefighter crews used a combination of hose reel jets and main line jets to extinguish the fire by 4:30am.
An investigation will be carried out this morning to determine the cause of the fire.
Last year, Southend Council approved plans for the floors above the Wimpy restaurant to be converted into nine new flats.
Essex Police remain at the scene.
