"Sunship Schiffahrtskontor KG confirms that all of its five crew members who were abducted during the boarding of the City of Xiamen off the coast of Nigeria, on 26 April 2013, were released on 11 May 2013," a statement said, identifying the hostages as Russian and Polish nationals.
Days after the attack, reportedly carried out by 14 well-armed gunmen who forced their way into the ship's saferoom, a Nigerian security source identified those abducted as Russian, Sri Lankan and a Myanmar national.
The German shipping firm refused to comment on the circumstances surrounding the release.
The region has seen a spate of similar incidents in recent months and it is widely assumed that companies pay the abductors in exchange for the release of their staff.
The authorities and the companies targeted typically do not comment on ransom payments.