The release of the 82 schoolgirls this month came after an initial group of 21 girls was released in October.
The humanitarian crisis is considered one of the worst in the world.
Flanked by three other women clad in black, the woman proclaims her loyalty to Boko Haram, which has been fighting the government since 2009 in an uprising that has killed over 20,000 people.
Dozens escaped in the initial melee, but more than 200 remained missing for more than two years.
Amina Ali was discovered last night in the Sambisa Forest area of Borno state by civilian vigilantes assisting the military and brought back to her home town of Mbalala, near Chibok.
Government spokesman Issa Tchiroma said Saturday that the raids targeted Boko Haram’s bases in the Madawaya forest earlier this month.
Nigeria and its neighbours Cameroon, Chad and Niger are due to hold a security summit in Abuja on May 14 with international partners including Britain, France and the United States.
One of every five suicide bombers deployed by Boko Haram in the past two years has been a child, usually a girl, according to the report.
In 2014, 276 schoolgirls were kidnapped by Boko Haram in Chibok, Boko Haram has carried out suicide bombings often using girls.
It is the first attack on Maiduguri since December 28, when Boko Haram attacked with rocket-propelled grenades and multiple suicide bombers, killing at least 50 people.
The shooting, burning and explosions from three suicide bombers continued for nearly four hours in the unprotected area.
A Nigerian military spokesman said that Boko Haram militants attacked the community of Dalori, about 5 km east of Maiduguri, on Saturday evening.
The attack killed at least 10 people and wounded about a dozen others.
About 60 people had wounds from bullets and shrapnel from explosive devices, she said. Other wounded people had to be sent to other hospitals in the city.
“Most of the victims were slaughtered and most of the wounded (had suffered) machete cuts,” Mustapha Karimbe, a civilian helping the Nigerian military fight Boko Haram.