Staffordshire Fire and Rescue Service chiefs say they have finished investigating Tuesday night's blaze at the Staffordshire park, and confirm it was started accidentally due to an electrical fault.
Fire crews were called at 10.30pm to the blaze at a toilet block in an area of the park.
Dave Steele, group manager head of the Eastern Service Delivery Group for SFRS, said: "The fire investigation at Drayton Manor has concluded and has been confirmed as accidental. It is believed that the fire was started by an electrical fault."
The fire, which covered an area of 30m by 10m, developed quickly due to the wooden roof construction of the building.
Flames were approximately 25m to 30m in height at the peak of the fire.
A total of 28 firefighters attended the scene, with the blaze put out at approximately 2am yesterday. It was put out after crews broke through the roof of an adjoining building and used jets to prevent the blaze from spreading.
A spokesman for Drayton Manor said: "Following the incident at the park, we can confirm that the fire is out and the area is cordoned off.
"We are very grateful to Staffordshire Fire and Rescue for all their support and are pleased to report that no one was injured by the fire, and all of the park’s animals are safe.
"We have now been able to survey the park and are relieved to confirm that the damage has been limited to a toilet block and store cupboard, both within Thomas Land. All of the rides remain intact with very limited damage."