The blaze at Bombardier Aerospace is now under control, the Fire Service says.
A spokesperson said that operations are now being scaled back after 50 crew members attended to the scene earlier tonight.
"We are pleased to report that the incident at Bombardier Aerospace is now under control, they added.
"Operations are being scaled back with a small number of resources remaining at the scene to damp down.
"The fire appears to have started in machinery and the cause of the incident is under investigation. At this stage the cause is believed to be accidental.
"There were no injuries at the incident."
Belfast Harbour Police have now reopened Airport Road following the incident.
