Kostomłoty [kɔstɔmˈwɔtɨ] is a village in the administrative district of Gmina Kodeń, within Biała Podlaska County, Lublin Voivodeship, in eastern Poland, close to the border with Belarus.

First written mention of the settlement comes from 1412 when the village was offered to the Augustinian Order from nearby Brest by the Lithuanian Grand Duke Vytautas.

In 1631 the Eastern Rite parish of St. Nicetas the Martyr was established, which accepted the Union of Brest of 1596 at some time during the 17th century, thus restoring communion the successor of St. Peter.

Following the Partitions of the Polish-Lithuanian Commonwealth the village first fall under Austrian rule and later became a part of the semiautonomous so-called Congress Poland which saved the parish from the first waves of repressions against the Ruthenian (Belarusian and Ukrainian) Greek-Catholic Church until the brutal Conversion of Chełm Eparchy by the Russian Empire in 1875.

After the Soviet victory in World War II most of those parishes were forcibly closed, only a few which were located in the People's Republic of Poland, rather than the Belarusian and Ukrainian SSR directly controlled by Moscow, could survive.