Thousands also fled to neighboring Cameroon and Chad in recent weeks, the agency said.
Hostilities have disrupted humanitarian operations and forced humanitarian workers to withdraw from some locations, and the destruction of livelihoods and infrastructure is widespread, UNHCR spokesman Babar Baloch told a news conference in Geneva. .
The recent rise in violence has also led more than 80,000 civilians to seek refuge in crowded camps or towns in Borno state where they are surviving in difficult living conditions, Baloch said.
More than 250,000 people have been displaced from northeastern Nigeria, and militant attacks on civilians have forced thousands of people to run for their lives every day, the UN said.
Two aid workers held hostage by the Boko Haram were executed last year after being abducted in a hospital at a homeless camp in Rann.
The UN agency said it would need $ 848 million to provide food and assistance to those affected by the crisis in Nigeria.
It also launched an additional appeal of $ 135 million to help those who were displaced by the insurgency in Lake Chad, which also suffered the impact of the attacks.
Military bases have been under intense attack by militants of the group in recent months, with reports of a large number of casualties in the army. Army leadership often denies these reports.
In November, he was forced to admit that 44 soldiers died in an attack on his military base in the village of Metele, Borno.
At least 15 people were killed in a series of attacks on four villages in Maiduguri, Borno state, in the same month.
Insurgents also claimed that Baga, a village on the outskirts of Maiduguri, and hundreds of villagers, including the village chief, fled their homes.