Ukraine is usually a major producer of cereals such as maize and wheat.
Russia’s invasion, and its blockade of Ukraine’s grain exports, have sparked grain and fertiliser shortages and put millions of people at risk of hunger.
The chair of the AU commission said there was an “urgent need for dialogue” to restore global stability.
Western countries have urged Russia to release Ukraine’s vast grain stores.
The blockade has sent food prices soaring.
“Africa is actually a hostage… of those who unleashed war against our state”, Mr Zelensky said in his speech.
He said his government was engaged in “complex negotiations” to unblock grain reserves trapped in Ukraine’s Black Sea ports.
“This war may seem very distant to you and your countries,” he told the AU. “But the food prices that are catastrophically rising have already brought [the war] to the homes of millions of African families.”
Mr Zelensky’s AU speech comes nearly 10 weeks after he first asked to address the continental body.
The BBC understands that 55 heads of state were invited to the virtual session, but only four attended. The rest of the countries sent representatives.