The UN under-secretary-general for humanitarian affairs was greeted by North Korean Vice Foreign Minister Pak Gil-Yon at an airport in Pyongyang, the official Korean Central News Agency said in a brief report.
The impoverished country was hit by famine in the 1990s which killed hundreds of thousands and has relied partly on international food aid ever since.
But donations to UN programmes have dwindled due to international irritation at the North's missile and nuclear programmes. Seoul suspended its annual shipment of rice and fertiliser in 2008.
The North this year asked the United States and other nations for food aid, but there are differences over its requirements.
UN agencies have said that some six million people in the country urgently need food.
But some South Korean officials are sceptical, saying North Korea wants to stockpile supplies for handouts to mark the 100th anniversary next year of the birth of founder Kim Il-Sung.
Many governments have also raised concerns that food aid could be diverted to the North's 1.1 million member army.
The North puts severe restrictions on the movement of foreigners, and the UN became so frustrated that it would only send aid to areas where it could get access.
The regime, however, has allowed more access this year as food shortages worsened, aid groups say.
UN agencies are now allowed to employ Korean-speaking international staff for the first time, Amos' spokeswoman, Amanda Pitt, said earlier.