The fire was reported on board a vessel at Victoria Terminal at 5.13am on Sunday
Some 13 fire appliances were involved in tackling a blaze on a ship at Belfast Port.
The blaze on board the ship at the Victoria Terminal on West Bank Road was reported at 5.13am on Sunday.
The Northern Ireland Fire and Rescue Service said 13 fire appliances and 61 firefighters attended the incident, including the Specialist Marine Response Team.
The blaze has been extinguished and investigations are ongoing, the spokesperson added.
Two sailings on the Stena Line service between Belfast to Cairnryan were cancelled after the fire on board the ship.
The ferry operator has confirmed the fire broke out in the exhaust system of their Superfast VII vessel and said the fire was brought under control by the crew itself before emergency services were called as a precaution.
No passengers were on board at the time of the incident.
The cancelled services affected included the 07.30 sailing from Belfast to Cairnryan and the 11.30 sailing in the opposite direction.