"The narrative on this humanitarian crisis can no longer be ignored and we are appealing to the international community to help us prevent the deaths of thousands of innocent civilians over the coming 12 months," the UN Deputy Humanitarian Coordinator Peter Lundberg said in a statement.
"This is the largest crisis on the African continent and I am confident that with the support of the international community and the private sector, we can begin to bring hope to the people of the northeast," he said.
The UN said the humanitarian response plan would address the needs of almost seven million people, in dire need of nutrition, food, shelter, healthcare and education.
"A projected 5.1 million people will face serious food shortages as the conflict and risk of unexploded improvised devices prevented farmers planting for a third year in a row, causing a major food crisis," it said.
Nigeria's junior budget minister Zainab Ahmed was quoted as saying the government would continue to demonstrate strong commitment to work with the international humanitarian community on the crisis.
The scale of humanitarian suffering became more apparent after Nigerian troops recaptured swathes of territory held by Boko Haramsince 2015.
The Boko Haram jihadist group has waged a brutal seven-year insurgency in Nigeria's mainly-Muslim north, with violence spreading to Cameroon, Chad and Niger.
At least 20,000 people have been killed and 2.6 million more displaced by the unrest, mostly in the northeastern states of Borno, Adamawa and Yobe, the epicentre of the Islamist uprising.
