They were among more than 1,000 residents killed in Ostrówki and the nearby village of Wola Ostrowiecka on 30 August 1943, during what is known in Poland as the Volhynia massacre.
The remains were recovered during recent exhumation work.
Karol Polejowski, deputy head of Poland's Institute of National Remembrance (IPN), described the findings as "a shocking truth."
He noted that most of those reburied at the Ostrówki cemetery were women and children, saying the unusually high proportion pointed to a genocide that had been planned and carried out in cold blood.
"It leaves one shaken, but it also forces deep reflection on what happened then," he said.
Culture Minister Marta Cienkowska called the reburial another step towards recovering historical memory, adding: "I have a sense that the Ukrainian side has an increasingly better understanding of how important this is for Poles."
Presidential adviser and Chełm mayor Jakub Banaszek pledged that efforts would continue to secure dignified funerals for all victims of the massacre.
Search and exhumation efforts are ongoing at other sites linked to the wartime killings, including Puźniki and Huta Pieniacka.
The Volhynia massacres were a series of ethnic killings carried out during World War II, primarily in 1943 and 1944, in which tens of thousands of Polish civilians were killed by the UPA in areas that are now part of western Ukraine.
The former villages of Ostrówki and Wola Ostrowiecka, once part of Poland's eastern Volhynia region, are now in Ukraine's Volyn region near the city of Kovel, after borders shifted following World War II.
The events remain one of the most sensitive issues in Polish-Ukrainian relations.
The Volhynia region, then part of Poland, was occupied by the Soviet Union in 1939 under the Molotov-Ribbentrop Pact before being seized by Nazi Germany in 1941.
(ał)
Source: IAR