Fourteen countries meeting in Oslo agreed -- with the US conspicuously absent -- to contribute the USD 672 million (634 million euros) over three years, including USD 457 million for 2017 alone.
But the United Nations has estimated the Lake Chad region, which includes Nigeria, Niger, Cameroon and Chad, needs USD 1.5 billion this year.
UN aid chief Stephen O'Brien was nonetheless optimistic that the target would eventually be met.
Boko Haram took up arms in 2009 in pursuit of an Islamic state in northern Nigeria.
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Its insurgency has since spread to neighbouring states bordering Lake Chad, with frequent suicide bomb attacks.
Still, the hardest hit area has been northeast Nigeria, where at least seven soldiers were killed in a Boko Haram attack on military positions on Wednesday, according to a security source.
The conflict, which has left around 20,000 people dead and forced more than 2.6 million others to flee their homes, has aggravated an already difficult humanitarian situation in one of the poorest regions of the world.
"Nigeria and countries contiguous to the Lake Chad are experiencing one of the largest and gravest humanitarian crises in the world," Nigerian Foreign Minister Geoffrey Onyeama said.
"They can't farm the land, markets have stopped working, and food prices have skyrocketed," French Development Aid Minister Jean-Marie Le Guen noted.
"Faced with these enormous needs the international response is still insufficient," he added.
The USD 672 million pledged over three years is aimed at helping 10.7 million people in need.
Abdou Dieng, regional head of the World Food Programme, described the challenge of getting aid to the "most vulnerable of the vulnerable".
The 14 donor countries who made firm commitments today were almost exclusively western European nations, with the exception of Japan and South Korea. But the United States, whose new administration has said it intends to slash its development aid budget, was not among them.