Zelenskiy's attendance at one of the world's premier diplomatic gatherings is meant to galvanise attention on his nation's 15-month fight against Russia.
Ukraine is the overwhelming focus of the summit, but the leaders of Japan, the United States, the United Kingdom, France, Germany, Canada and Italy, as well as the European Union, are also working to address global worries over climate change, AI, poverty and economic instability, and nuclear proliferation.
Bolstering international support is a key priority as Ukraine prepares for what's seen as a major push to take back territory seized by Russia in the war that began in February last year.
"Japan. G7. Important meetings with partners and friends of Ukraine. Security and enhanced cooperation for our victory. Peace will become closer today," Zelenskiy tweeted after his arrival.
US national security adviser Jake Sullivan said that President Joe Biden and Zelenskiy would have direct engagement at the summit. On Friday, Biden announced his support for training Ukrainian pilots on F-16 fighter jets, seen as a precursor to eventually providing those aircraft to Ukraine.
"It is necessary to improve (Ukraine's) air defence capabilities, including the training of our pilots," Zelenskiy wrote on his official Telegram channel.
Zelenskiy met India's Prime Minister Narendra Modi on the sidelines of the summit, their first face-to-face talks since the war, and briefed him on Ukraine's peace plan, which calls for the withdrawal of Russian troops from the country before any negotiations.
India, the world's largest democracy, has so far avoided outright condemnation of Russia's invasion.
Russian Foreign Minister Sergey Lavrov criticised the G-7 summit for aiming to isolate both China and Russia.
"The task has been set loudly and openly: to defeat Russia on the battlefield, but not to stop there, but to eliminate it as a geopolitical competitor...Look at the decisions that are now being discussed and adopted in Hiroshima, at the G7 summit, and which are aimed at the double containment of Russia and China," he said.
The G7, however, has vowed to intensify the pressure.
"We reaffirm our unwavering support for Ukraine for as long as it takes to bring a comprehensive, just and lasting peace," the group said in a statement.
Another major focus of the meetings was China, the world's No. 2 economy.
The G7 said they did not want to harm China and were seeking "constructive and stable relations" with Beijing, "recognising the importance of engaging candidly with and expressing our concerns directly to China."
They also urged China to pressure Russia to end the war in Ukraine and "support a comprehensive, just and lasting peace."
The G7 leaders have rolled out a new wave of global sanctions on Moscow as well as plans to enhance the effectiveness of existing financial penalties meant to constrain President Vladimir Putin's war effort. Russia is now the most-sanctioned country in the world, but there are questions about the effectiveness.
The leaders began the summit with a visit to a peace park dedicated to the tens of thousands who died in the world's first wartime atomic bomb detonation. Japan's Prime Minister Fumio KishidaKishida, who represents Hiroshima in parliament, wants nuclear disarmament to be a major focus of discussions.
Biden, who scrapped plans to travel on to Papua New Guinea and Australia after his stay in Japan so that he can get back to debt limit talks in Washington, also met with leaders of the so-called Quad partnership, made up of Japan, Australia, India and the United States.
