A parked van was damaged in the blast. There were no reports of injuries.
The remains of a bomb, believed to be a small home-made device, was found hidden in a trash bin in the carpark.
Police and other officials are at the scene now and the area has been blocked off.
A OrBorJor employee told The Phuket News she was working inside the OrBorJor office when she clearly heard the bomb and that it was very loud. Initially she thought it was an electricity generator exploding outside.
"I was frightened," she said.
Another witness was at the Phuket Provincial Hall PR Office – around 20 metres away – when she heard the noise and saw smoke coming out of the area where the bomb exploded.
Phuket Provincial Police Deputy Commander Saneh Yawila said, "We do not think it was politically motivated."
More details to come.