According to the UN, about 12 million people across the region, and four million in Somalia alone, are in need of food aid, Daily Mail reported.
Getting aid to the starving is a 'race against time', said a top humanitarian official for Somalia, while also warning that the famine is likely to spread before the end of the year.
Mark Bowden, who heads the UN office coordinating humanitarian aid to Somalia, said: 'This isn't a short-term crisis.'
There are fears as many as 750,000 people could starve to death. This is a rise of 66 percent from July. Hundreds of Somalis are dying every day, at least half of which are children.
Bowden said the four million Somalis in need of aid represented more than half of the country's entire population.
The southern Bay region is the latest to be declared a famine zone.
Nearly 60 per cent of people there are acutely malnourished - four times the rate at which an emergency is declared.
'I've not seen anything like it,' said Grainne Moloney, the head of the food security unit.
Famine has now affected six areas, including four southern Somali regions and two settlements of refugees.
The UN says tens of thousands of people already have died in Somalia due to the severe violence, drought and famine.
Over 150,000 refugees have sought aid in the last few months. Families in Kenya, Ethiopia and Djibouti have also been affected.