"Nigerian army troops rescued another Chibok schoolgirl at Pulka" last evening, army spokesman Sani Usman told AFP, adding he would give details of the rescue operation later.
Pulka is outside the town of Gwoza in Borno state near the Mandara mountains separating Nigeria from Cameroon.
The news came barely one month after 21 other Chibok girls were released by Boko Haram.
They were freed following negotiations between the Nigerian government and Boko Haram brokered by the International Committee of the Red Cross (ICRC) and the Swiss government.
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More than 200 schoolgirls were seized by the Islamist group from their hostels in the remote town of Chibok in April 2014.
The mass abduction drew global anger and attracted unprecedented attention to the seven-year Boko Haram insurgency.
The insurgency in Nigeria's mainly-Muslim north has killed at least 20,000 people and made more than 2.6 million homeless since 2009.