"We are bringing our people home," Ukrainian President Volodymyr Zelensky said in a social media post.
"The first stage of the '1000-for-1000' exchange agreement has been carried out," he wrote, sharing photos of freed Ukrainians, many draped in the country's blue-and-yellow flag.
Zelensky said the deal was reached during a meeting in Turkey and stressed the importance of seeing it fully implemented.
The POW exchange was the only deal made during last week's talks in Istanbul, the first direct ceasefire negotiations between the two countries since the early weeks of the war, US public broadcaster NPR reported.
US President Donald Trump announced the exchange earlier on Friday, saying on social media that "a major prisoner swap was just completed between Russia and Ukraine."
He congratulated "both sides on this negotiation," adding that "this could lead to something big."
Ukrainian officials said 270 soldiers and 120 civilians were included in Friday's exchange, NPR reported.
Russia launched what it calls a "special military operation" against Ukraine on February 24, 2022, starting the largest armed conflict in Europe since World War II.
Friday was day 1,185 of the war.
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Source: IAR, PAP, NPR, ukrinform.net