'We commit to eliminating hunger and to securing food for all, today and tomorrow,' said the declaration, agreed by negotiators in a summit committee at the end of the three-day conference in Rome.
However anti-poverty campaigners said rich countries needed to commit to long-term action to boost food output and free up trade.
The summit of 183 countries narrowly avoided an embarrassing failure when Latin Americans protested at points in the declaration.
Delegates and campaigners agreed the summit had succeeded in putting soaring food prices at the top of the global agenda.
'If nothing else, nations came together to recognise the problem,' said US Agriculture Secretary Ed Schafer.
The UN Food and Agriculture Organisation called the summit to discuss the impact of poor harvests, high fuel costs and rising demand, especially from fast-growing Asian countries.
Commodity prices have doubled over the last couple of years and the World Bank says 100 million people risk joining the 850 million already going hungry.
The Organisation for Economic Cooperation and Development sees prices of rice, corn and wheat retreating from peaks but still up to 50 percent higher in the next decade and the FAO says food output must rise 50 percent by 2050 to meet demand.
'While we welcome the attention that the summit has drawn to addressing the emergency needs of the food price crisis, governments haven't made any serious long-term commitments,' said campaign group ActionAid.
Aid agencies and campaigners urged rich nations to make more tangible decisions at July's Group of Eight summit in Japan.
'There is a growing awareness that rich countries cannot continue to give with one hand and take away with the other,' said Barbara Stocking of Oxfam.
'Unless unfair international trade, biofuels and agriculture policies are changed the crisis for developing countries' agriculture will continue.'
Free trade was a sticking point. Grain and beef exporter Argentina objected to criticism in the declaration of export curbs like those it has imposed to shield consumers from food inflation -- measures which have angered its farmers.
Washington's Schafer said countries should understand that such restrictions cause food inflation. Asian rice stockpiling is blamed for high rice prices that have even led to riots.
'We understand that countries want to protect their food supply and make sure that there's enough food for their own citizens but when there's a lock-out from the marketplace ... prices actually go up,' Shafer told reporters in Rome.
Cuba and regional allies including Venezuela and Argentina voiced objections to a summit declaration which Cuban delegate Orlando Requeijo Gual said 'frankly neglects the vital needs of those who suffer from hunger'.
Criticising US sanctions on communist Cuba, he hit out at the 'sinister strategies of using grain for fuel', a reference to biofuels, which critics say divert crops from food to cars.
The United States and Brazil defended using maize and sugar cane respectively to make ethanol to fuel cars, saying it is a minor factor in food price inflation. The declaration referred to both the 'challenges and opportunities' of biofuels.
Although the summit was not meant to produce promises of aid or set new global policies, it should put hunger higher up on the agenda of the G8 summit next month.
By then UN Secretary General Ban Ki-moon is due to have issued an action plan.
The Rome debate on potential benefits to poor farmers of new global trade rules will also feed into a push to conclude the Doha round of World Trade Organisation talks.
'This is at the top of the global agenda and it's none too soon,' said Josette Sheeran, head of the World Food Programme which delivers emergency supplies.
'Hunger is on the march.'
