Among the topics high on the agenda in Cornwall is the recovery from the coronavirus pandemic, APA reports citing BBC.
Ahead of the talks starting Boris Johnson says the UK will start donating coronavirus vaccines to poorer countries in the next few weeks.
More than 100 million surplus doses will be delivered in the next year, he says.
It follows a pledge from US President Joe Biden of half a billion doses of Pfizer vaccines to 92 low and middle-income countries and the African Union.
The first five million doses from the UK will be given by the end of September, with another 25 million by the end of the year.
The prime minister says: "As a result of the success of the UK's vaccine programme we are now in a position to share some of our surplus doses with those who need them.
"In doing so we will take a massive step towards beating this pandemic for good."
He hopes his fellow leaders at the summit will "make similar pledges so that, together, we can vaccinate the world by the end of next year".