Popular community station Gateway FM, located in the Galleries, will have to replace all of its equipment, costing thousands of pounds.
Firefighters were called to the Basildon town centre mall just after 11.30pm on Wednesday.
Five crews from Basildon, Orsett and Grays spent almost an hour battling the flames.
The station’s inhouse sprinkler system was activated and neighbouring shops on the top floor were flooded. They remained closed yesterday as a clean-up operation began.
However, the showwent on for Gateway FM, which is being broadcast from a home studio.
Yvonne Williams, managing director of the station, said: “The fire has caused a tremendous amount of damage. The studios are completely out of operation, but fortunately we have a fail-safe alternative, sowe can still operate a service.
“It might be below our normal service, but it gets us by.
“As far as the Eastgate is concerned, it has caused big problems.
Without the sprinkler system, the whole of the shopping centre could have been destroyed.
“Some of the other retailers have suffered enormously and lost an enormous amount of stock because of all the water which poured into the centre.
“As far as the studios are concerned, it’s a case of new equipment being purchased and installed, and thatwill take time.”
It is thought someone broke into the Eastgate shopping centre before lighting the fire and fleeing.
A spokesman for Essex Police said: “A man has been arrested in connection with a fire at Basildon’s Eastgate shopping centre.
“Police were contacted at 11.55pm on Wednesday following reports of a blaze on the top floor of the building.
“A 26 year-old man, of no fixed address, was arrested several hours later on suspicion of arson.
“He is being questioned by officers at Basildon police station.”