Foreign Minister Boris Johnson visited Maiduguri, the capital of Borno State and epicentre of the Boko Haram organisation, to meet some of those involved in the fight.
The Islamist militant group has increasingly used child suicide bombers and targeted civilians in its eight-year insurgency which have left at least 20,000 dead and displaced more than 2.6 million.
“In Maiduguri, I met casualties of Boko Haram violence, including bomb and gunshot victims, and saw for myself the displacement of people that brutality and poverty have created,” Johnson said in a statement.
The £200 million ($260 million, 220 million euros) will help supply food to 1.5 million people facing famine as a result of the bloody insurgency while providing treatment for 120,000 children at risk of malnutrition and assisting 100,000 children with educational needs.
British military teams will also continue to help prepare Abuja’s security forces for counter-insurgency operations, having already helped to train 28,500 Nigerian personnel.
The uprising by Boko Haram, which is seeking to impose hardline Islamic law in Nigeria’s mainly Muslim north, has included a campaign of civilian kidnappings.
More than 200 schoolgirls were abducted by Boko Haram from their school in the remote town of Chibok in April 2014.
A total of 106 of the kidnapped girls have been released, rescued or escaped after more than three years in captivity, while 113 are still being held.