Senior members of the World Food Programme (WFP) - headed by its Executive Director Cindy McCain - have held meetings in Dublin with non-governmental organisations and politicians, including Minister for Agriculture Charlie McConalogue.
Ms McCain, widow of late US Republican Senator John McCain, said that 345 million people worldwide are in acute food insecurity, double the number of three years ago.
"The reasons for this are climate change, Covid-19 and conflict in Africa and in Ukraine."
Those living in Sudan are being hit hardest, she added, with big numbers fleeing war and drought that have made farming impossible.
Ms McCain said that donor fatigue is affecting the WFP's ability to assist people, and that it has had to cut back on aid in some places.
The WFP is the world's largest humanitarian organisation, with 23,000 staff and a presence in 120 countries.
Ireland has committed €75m to the programme over a three-year period and the Department of Agriculture is the lead government department in dealing with the organisation.
Ireland has a seat on its executive board.
Ms McCain also met with members of the Joint Oireachtas Committee on Agriculture as well as non-governmental organisations.
She said that Ireland "is a committed friend to the WFP and we are working closely together to reverse the global hunger crisis.
"The flexible funding provided by the Irish Government is critical to help us tackle hunger and malnutrition, support vulnerable communities adapting to climate change and build more resilient food systems capable of feeding every person on our planet."
Ms McCain noted that there is enough food in the world to feed everyone, but she said that Russia's blockade of Ukrainian grain exports has added to "a perfect storm", meaning that "literally, the world is on fire right now".
Asked about how to get grain moving out of Ukraine again, she said: "Put the pressure on Russia.
"Russia is holding food hostage and we have to get the Black Sea grain deal open.
"We need to be able to get our ships and other ships in to get the grain out and we need a humanitarian corridor that is safe to do that."
Minister McConalogue welcomed Ms McCain, saying: "Ireland is a committed partner to WFP and our multi-annual flexible funding facilitates them to help those most in need.
"I want to use the visit by the executive director to highlight the importance of our continued support to the WFP and to encourage governments around the world to take steps towards giving them the reliable funding they require."
The world needs Irish beef and dairy products, she added.
Earlier, Ms McCain noted that the WFP has not yet raised half of the $14 billion (€13bn) it raised last year, and that donor fatigue is a large part of this poor performance.
"Not just the fatigue aspect, but people are tired of wars, they're tired of talking about this, they're tired of hearing about it.
"We can't let them be tired because it's too much of a tragedy if we don't take care of it. It's kind of a malaise, almost, with regard to food aid and aid in general right now," she told RTÉ's Morning Ireland.
Throughout Africa and in parts of the Middle East, particularly Yemen, cuts to food aid rations mean that, although people are still receiving some help, they are not getting enough.
Ms McCain said that while the United States has always been generous to the WFP, campaigning for the presidential election means that "people are not talking about what's important right now in the world".
The public needs to refocus on the fact that people are going to "starve to death" if money is not raised, she warned.
The world needs everybody to help feed all those living in it, she urged.
