“The foreign sailors, including seven Russians and one Ukrainian, have been rescued. They were rescued by our operatives in Delta state,” Navy spokesman Captain Suleman Dahun told AFP.
He said the sailors were released “unhurt and they are back in their countries”.
It was not immediately clear if ransom money was paid before they were released.
The sailors were taken hostage on February 5 after their cargo vessel, the BBC Caribbean, was attacked by sea pirates off the coast of the volatile Niger delta region.
Three people, who remained on board, managed to run away from the pirates and took the vessel to Spain’s Las Palmas, before returning to Russia.
The BBC Caribbean belongs to German company Briese Schiffahrt and is a multipurpose vessel intended for dry cargo. It flies the flag of Antigua and Barbuda, according to the company’s website.
Ship hijackings have become more frequent in Nigeria since President Muhammadu Buhari in 2015 announced he was winding down an amnesty to former militants in the oil-rich Niger delta region.
The number of pirate attacks off Nigeria rose from 14 in 2015 to 36 last year, according to the International Maritime Bureau.