Half of them were children under the age of five, says the report by the UN food agency and the US-funded Famine Early Warning Systems Network.
An estimated 4.6% of the total population and 10% of children under five died in southern and central Somalia. In Lower Shabelle, 18% of children under five died and in Mogadishu 17%.
"The report confirms we should have done more before the famine was declared," said Philippe Lazzarini, UN humanitarian co-ordinator for Somalia. "Warnings that began as far back as the drought in 2010 did not trigger sufficient early action,"
The number of deaths was higher than the estimated 220,000 people who died during the 1992 famine.