In addition to attending a meeting with G7 leaders and other invited guests, Zelenskiy held back-to-back bilateral meetings.
Outreach to the so-called "Global South", shorthand for some low- and middle-income countries including India, has been a focus at this year's summit, which is being hosted by Hiroshima.
The interest isn't just altruistic.
The world's rich democracies are looking askance at China's heavy footprint across the developing world and worry about its sway over supply chains and critical minerals.
Some of China's lending has left developing countries "trapped in debt", US Treasury Secretary Janet Yellen has said.
China, which has lent hundreds of billions of dollars to build infrastructure in developing countries, has called those remarks "irresponsible" and said the United States should take practical action to help developing countries.
Japan and Germany have for years been pushing for a reform of the United Nations Security Council.
Together with Brazil and India they have pressed for permanent seats.
That effort got a renewed push at the G7 on Saturday when Japan's Prime Minister, Fumio Kishida, and Brazil's President, Luiz Inacio Lula da Silva, met on the sidelines of the summit and agreed to work for reform at the Council as non-permanent members.
German Chancellor Olaf Scholz has said international organisations need to change as the world has.
The G7's economic clout has also shrunk.
The seven nations' economies accounted for 29.9% of global GDP in 2023, down from 50.7% in 1980, according to the International Monetary Fund.
Japan's Kishida has said his country's role is to bridge the gap between the G7 and the Global South in areas such as energy and food security.
Tokyo announced a new security aid programme this year, the Overseas Security Aid, which will provide military equipment to help developing countries bolster security with an eye on countering Chinese pressure, a Japanese official said.
'Ukraine is getting stronger' - Zelenskiy after G7 talks
Ukrainian president Volodymyr Zelenskiy released a video statement on Saturday, saying that Ukraine will get stronger after the G7 Summit in Japan.
British Prime Minister Rishi Sunak was among the G7 leaders Zelenskiy met with as he attended the summit as an invited guest.
The Ukrainian leader said he thanked Sunak for helping reinforce Kyiv's aerial abilities as it battles Russian forces within its own borders.
“This is historic,” Zelenskiy said.
US President Joe Biden told G7 leaders on Friday that Washington supports joint allied training programmes for Ukrainian pilots using F-16 fighter jets, senior US officials said, providing another significant endorsement as Kyiv seeks to boost its air power against Russia.
Although the US officials did not say which countries would participate, Sunak said the UK would work with the Netherlands, Belgium and Denmark "to get Ukraine the combat air capability it needs."