"A staggering 345 million people are now experiencing acute hunger, a number that has more than doubled since 2019," they said in a statement.
"Despite promises from world leaders to never allow famine again in the 21st century, famine is once more imminent in Somalia. Around the world, 50 million people are on the brink of starvation in 45 countries," they said.
Pointing out that as many as 19,700 people are estimated to be dying of hunger every day, the NGOs said that this translates to one person dying of hunger every four seconds.
"It is abysmal that with all the technology in agriculture and harvesting techniques today we are still talking about famine in the 21st century," Mohanna Ahmed Ali Eljabaly from the Yemen Family Care Association, one of the letter's signatories, said in the statement.
"This is not about one country or one continent and hunger never only has one cause. This is about the injustice of the whole of humanity," he said.
"We must not wait a moment longer to focus both on providing immediate lifesaving food and longer-term support so people can take charge of their futures and provide for themselves and their families."