Ukraine's parliament commissioner for human rights, Dmytro Lubinets, confirmed in a social media post that the ceasefire had begun.
"As head of the Ukrainian negotiating team, I confirm that the Ukrainian side is honouring its commitments," he wrote on Facebook.
Oleshky was seized by Russia during the first days of its full-scale invasion in February 2022.
Residents were trapped with scarce food between Ukrainian positions across the Dnipro River and Russian forces to the east.
The city was home to 24,000 people before the war. Now Ukraine estimates that some 6,000 people remain in the city and its surrounding areas, including 200 children.
The White House said last week that Melania Trump had secured the ceasefire in Oleshky.
"Non-military, civilian leaders from both countries will work together to visit Oleshky residents in their homes and determine the level of assistance they require," she said in a press release.
While the US first lady is relatively lower profile than some of her predecessors - and only occasionally seen at White House events - she has become involved in addressing humanitarian issues stemming from the Russia-Ukraine war.
In August 2025, she penned a letter to Putin, telling him it was "time to protect children and future generations worldwide".