The ministry said the St. Patrick ship, owned by Miden Oil Servicing Company, had been seized by the company's Nigerian staff in protest over four months' of wage arrears.
The ship's 25-men crew included two Ukrainian nationals, two British nationals, three citizens of India and one Lithuanian.
"The company workers who hijacked the ship were unarmed, their goal was to pressure the company management over wage arrears," the Ukrainian ministry said.
"The crewmen were released and the ship returned as a result of talks between Nigeria's security service and the company," the ministry said, giving no further details.
All the crew are said to be in good health.
Nigeria, Africa's top oil producer, has been plagued by kidnappings of foreign oil workers for ransom by militants and criminal groups as well as oil tapping and the hijackings of vessels loaded with oil.
