Somalia declared a national disaster last month as the number of people going hungry hit three million.
The Central Emergency Response Fund (CERF) is releasing the funds to the Food and Agriculture Organization (FAO) in the hope it will help stave off catastrophe in the civil-war wracked country, just five years after the last famine.
Somalia declared a national disaster last month as the number of people going hungry hit three million, with 6.2 million people in total expected to face acute food insecurity over the next three months.
The Rome-based FAO said the funds would go to helping rural communities that have been hit particularly hard, as crops fail, cattle die and wells dry up.
The head of the UN's Office for the Coordination of Humanitarian Affairs (OCHA), Stephen O'Brien, said the loan was "part of the efforts to avert a humanitarian catastrophe".
"The loan will bridge a crucial gap and allow FAO to immediately save lives and the livelihoods of farmers and herders until additional funds from donors are received," he said, amid pessimism from meteorologists about the prospect of rain any time soon.
Somalia is among three nations on the verge of famine, along with Yemen and Nigeria.
In South Sudan, 100,000 people are already in famine conditions. In total the disaster threatens the lives of 20 million people.
It is the third famine in the 25 years that Somalia has been embroiled in civil war and anarchy, including one in 2011 which left 260,000 people dead.