"We believe that the purpose of aid must be to create the conditions where it's no longer needed, to help people become self-sufficient, provide for their families and lift their standards of living."
Mr Obama, who has relatives in Kenya, said he had drawn on his family's personal experience in his discussions with other world leaders.
The US will reportedly contribute some $3.5bn to the programme.
Mr Obama met representatives of Angola, Algeria, Nigeria and Senegal in L'Aquila, where the summit is being held. He will also meet Pope Benedict XVI in Rome before embarking on an African tour later on Friday.
African leaders had earlier urged G8 nations to live up to past aid pledges.
BBC economics correspondent Andrew Walker says the idea is to put more emphasis on helping people feed themselves.
That is to be achieved with more investment in the agriculture of developing countries, and the G8 nations - Britain, Canada, France, Germany, Italy, Japan, Russia and the US - will provide significant resources, our correspondent adds.
Obama insisted Africa can be self-sufficient when it comes to food
However, although the total amount of overseas development aid (ODA) was increased in 2008, the rich countries are still behind on their target to double aid that was made at the G8 Gleneagles Summit in 2005 - and Italy is among the laggards. Not all the money pledged to the agriculture initiative at the summit will be new funding.
Kanaya Nwanze, president of the International Fund for Agricultural Development, told the BBC that he welcomed the announcement of more investment in agriculture in the developing world.
"It is time for us to switch because food security is not just food aid," he said.
"It is the ability of people to produce food locally and for them to be able to have access to local markets."
Ethiopian Prime Minister Meles Zenawi, who also attended Friday's talks, told Reuters news agency beforehand that the key message from African nations was that the G8 had to live up to its commitments.
Aid organisations have criticised some members for failing to deliver on the promise made at the 2005 G8 summit to increase annual aid levels to sub-Saharan Africa by $25bn by 2010.
Italy, the present summit host, has come under particular pressure for cutting, rather than increasing, aid this year.
Prime Minister Silvio Berlusconi has said the global economic crisis and Italy's mounting debts are responsible for a delay in Rome meeting its promises.
On Thursday, when the summit focused on climate change, leaders from both developed and developing nations agreed that global temperatures should not rise more than 2C above 1900 levels.
That is the level above which, the UN says, the Earth's climate system would become dangerously unstable.
It is time for us to switch because food security is not just food aid
Kanaya Nwanze International Fund for Agricultural Development
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