The MV Brave Commander, which left Istanbul on Wednesday, is due to arrive in Yuzhne, east of Odessa on the Black Sea coast, the UN's World Food Program said.
It will collect Ukrainian wheat grain purchased by the WFP, according to the agency's spokesman, Tomson Phiri, who stated "This is obviously the first shipment of humanitarian food assistance under the Black Sea Grain Initiative."
WFP has purchased an initial 30,000 tons of Ukrainian wheat. MV Brave Commander has a capacity of 23,000 tons.
"The remaining balance will be loaded and shipped on another vessel soon," Phiri said.
"WFP is hopeful that the MV Brave Commander is the first of what will now become regular shipments out of Ukraine as the Black Sea Grain Initiative gains momentum."
It is not yet clear when the ship will depart and WFP did not release details of where it would be heading.
"Loading and moving ships in and out of ports in the context of the current conflict is a complex operation," said Phiri.
"Getting Ukrainian grain to WFP's humanitarian operations in places like Ethiopia, Somalia and Yemen will ensure a double benefit to both Ukraine's economy and famine risk populations in areas of the world hardest hit by the global food crisis."
The blockage of deliveries from Ukraine and Russia -- two of the world's biggest grain exporters -- has led to a spike in prices and made food imports prohibitively expensive for some of the world's poorest countries.
A record 345 million people in 82 countries face acute food insecurity and up to 50 million people in 45 countries are on the edge of famine and risk being tipped over without humanitarian support, Phiri said.
The first shipment of Ukrainian grain under the deal that lifted a Russian blockade of Ukraine's ports and established safe corridors through the naval mines laid by Kyiv left Odessa on August 1.
On July 22, Kyiv and Moscow signed a landmark deal with Turkey to unblock Black Sea grain deliveries, following Russia's February invasion of Ukraine.
Turkey has opened a special facility in Istanbul at the mouth of the Black Sea to oversee the exports. It is staffed by civilian and military officials from the warring sides and delegates from Turkey and the UN.