Zelenskiy told Ukrainian diplomats in a speech published on the president's website that almost 40 countries would be represented at the meeting in Jeddah on August 5 and 6.
"We are working on making it (the summit) happen this autumn," he said.
"Autumn is very soon, but there is still time to prepare for the summit and involve most of the world's countries."
Zelenskiy and his team are working with allies to build broad support for a "peace summit" that would endorse principles to underpin a settlement to end the war started by Russia's full-scale invasion almost 18 months ago.
The summit would build on a 10-point plan outlined by Ukraine last autumn that has been actively promoted by Zelenskiy.
His vision for peace calls for the full restoration of Ukraine's territorial integrity and a full withdrawal of Russian troops, the protection of food and energy security, nuclear safety, the release of all prisoners and other points.
No venue has been agreed for the summit yet.
Officials from Ukraine and its allies have said the summit would not involve Russia.
Meanwhile, Brazilian President Luiz Inacio Lula da Silva said his country is working for peace in Ukraine but neither its leader nor Russia's are prepared to talk peace.
"Neither (President Vladimir) Putin nor Zelenskiy are ready," Lula told foreign correspondents in a news conference, adding that peace proposals he is seeking with other countries will be ready when Russia and Ukraine are willing to negotiate.
"Brazil's role is to try to arrive at a peace proposal together with others for when both countries want it," he said.
Lula has tried to form a group of neutral countries to get peace talks going.
He has been criticised for saying that Ukraine and Russia are equally responsible for the war.
The progressive president, who was elected last year for a third term, lashed out at world powers backing Ukraine and the permanent United Nations Security Council members for not stopping war.
"The UN Security Council has not worked. United States invaded Iraq, France and England invaded Libya, now Russia. And everyone has veto power," he stated.
Lula said the G7 group of advanced economies should no longer exist since the creation of the larger G20 group of leading and emerging economies.
"I hope once and for all that people see that discussing politics in the G7 is out of date. After the G20, there shouldn't even be the G7," he said.
Lula said the BRICS group of emerging economies should allow new members "as long as they meet the requirements".
His country has become the main opponent of expanding BRICS but the Brazilian president indicated that could change to make the five-country group stronger.
"I think it's extremely important for Saudi Arabia to join the BRICS (and) for the United Arab Emirates join, if they want to. Argentina too," he said.
Lula said the New Development Bank created by the BRICS should be more generous than the International Monetary Fund.
"The bank exists to help save countries and not to help sink countries, which is what the IMF often does," he said.
