"The prime minister and President Zelenskiy will be meeting in Downing Street this afternoon," a spokesperson for Starmer's office said on Saturday.
The meeting follows an extraordinary public spat between Zelenskiy and US President Donald Trump at the White House over the war with Russia.
Zelenskiy had seen the meeting in the Oval Office as an opportunity to convince the United States not to side with Russian President Vladimir Putin, who ordered the invasion of Ukraine three years ago.
Starmer spoke to both Trump and Zelenskiy on Friday and expressed his "unwavering support" for Ukraine, echoing similar statements of backing for Zelenskiy from other European leaders.
US support for Ukraine is "crucial," Zelenskiy said as he arrived in the UK.
The Ukrainian leader's plane, emblazoned with the country's flag, landed at London's Stansted Airport on Saturday morning and was met by a convoy of cars.
Zelenskiy struck a conciliatory tone in a string of posts on X after arriving in the UK.
Ukraine was "very grateful to the United States for all the support," Zelenskiy said.
"I'm thankful to President Trump, Congress for their bipartisan support, and American people," he added.
"It's crucial for us to have President Trump's support. He wants to end the war, but no one wants peace more than we do.
"We are the ones living this war in Ukraine.
"It's a fight for our freedom, for our very survival."
The verbal stoush at the White House was met with a volley of supportive messages from European leaders who are set to gather in London on Sunday.
Starmer's talks at Downing Street on Sunday are expected to feature European leaders discussing efforts to police a future Ukraine peace deal.
Starmer believes a deal will have to involve US military assets providing surveillance, intelligence and potentially warplanes giving air cover to deter Russian forces from launching another bid to conquer its neighbour.
The summit on Sunday in London will include leaders from France, Germany, Denmark, Italy, Netherlands, Norway, Poland, Spain, Turkey, Finland, Sweden, the Czech Republic and Romania, as well as the NATO secretary-general and the presidents of the European Commission and European Council.
Three people were killed in a Ukrainian attack on a Russian-occupied part of Kherson region in southern Ukraine, Russian-installed governor Vladimir Saldo said on Saturday.
Two of them were killed on a road between the villages of Nova Maiachka and Obryvka, while the third was killed in the town of Oleshky, Saldo said via his channel on Telegram.
Five other people were injured of varying degrees of severity, Saldo said.
with PA and AP
