FAO Director-General José Graziano da Silva thanked the world's food and agriculture workers for their contribution to the "amazing achievement" of increasing sustenance for all even as the world population tripled since 1945.
But with around 800 million people still suffering from undernutrition, two big challenges lie ahead, he told assembled dignitaries.
"First, we must quickly translate increases in food availability into better nutrition for all. Second, we must accelerate the shift of food production and consumption towards truly sustainable systems," Mr Graziano da Silva said.
Mr Graziano da Silva noted that increased production alone is not enough, and increasing the power of the poor to buy food offers an affordable key to hunger eradication, as shown by countries like India, Brazil and Ethiopia.
Social protection allows the hungry to "become empowered to escape hunger through their own efforts, thus lead dignified and productive lives," he added.
Pope Francis sent a message supporting these ideas of improving food access for the poor, adding that unequal resource distribution tends to lead to violence.
The UN Secretary-General Ban Ki-moon emphasised the scale of food waste and loss, estimated as around a third of all the food produced globally. "People everywhere know that waste is a disgrace," he said.
"Feeding the planet is inseparable from the word 'peace'," said President Sergio Mattarella of Italy. "Only joint action can assure food security and the sustainable use of natural resources. Unilateral action does not lead to success."
Fair returns for farmers needed to combat hunger
EU-wide agricultural association Copa-Cogeca marked World Food Day by urging the EU to develop a more rigorous policy to combat hunger and malnutrition.
The group's Secretary-General Pekka Pesonen said that more food would have to be produced with less resources in order to feed a growing world population sustainably.
However, he also emphasised the importance of fair returns for farmers, to give them a viable future and encourage investment and new entrants.
"We need a more balanced, fairer food chain so that farmers get a better return for their produce instead of being squeezed unfairly by retailers.
"We also need stronger measures under the CAP to better manage the market to deal with the extreme market volatility as well as further development of futures markets and risk management measures," he said.