Biden's plane touched down at a military airport to the south of the host city, Hiroshima, in southern Japan.
German Chancellor Olaf Scholz also arrived on Thursday, before the official start of talks on Friday.
In addition to the US and Germany, the G7 includes France, Italy, Britain, Japan and Canada.
European Union leaders will also be at the meeting.
There was speculation Ukrainian President Volodymyr Zelenskiy might also travel to Japan for the summit, however, the Japanese government said Zelenskiy would attend the summit via video link, Japanese news agency Kyodo reported.
Earlier, statements from Zelenskiy's entourage raised the possibility the president might attend the meeting in person.
During a visit to Ukraine, Japanese Prime Minister Fumio Kishida had invited Zelenskiy to take part via video link.
Japan currently holds the rotating G7 presidency.
Kyodo, citing Ihor Shovkva, the deputy head of the Ukrainian presidential office responsible for foreign policy, initially reported an in-person meeting between Zelenskiy and the G7 heads of state and government would depend on the military situation.
The war in Ukraine, the state of the global economy, denuclearisation, and the West's relationship with China are set to top the agenda of the leaders' discussions.
The talks are being accompanied by extensive security measures.
Police said some 24,000 security personnel from all over Japan would be on duty during the meeting, which continues until Sunday.
The Peace Memorial Park, which the heads of state and government are visiting for the opening ceremony, has been cordoned off with a two-metre-high fence.
Access to the atomic bomb dome is also blocked.
The burnt-out building was damaged when the US dropped an atomic bomb on the city in 1945 at the end of World War II and is now a symbol of peace and a testament to the horror of nuclear weapons.
Scholz said on Thursday he expected the summit to send a clear signal against the use of nuclear weapons.
"This is a very symbolic place here," he said.
"The nuclear catastrophe that was experienced here is a reminder to all of us that we must ensure that nuclear weapons are never used."
Boats were patrolling up and down the river around the Peace Park on Thursday.
Some 140 schools were closed due to severe traffic restrictions.
The tightened security measures come against the backdrop of a recent attack on Kishida, in which he was unharmed.
His predecessor Shinzo Abe had been shot dead at an election rally a few months earlier.
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