The Jewish community of Ostrowiec was relatively young, with the earliest extant reference to the presence of Jews in the town dating only to 1886. In 1913, there were some 100 Jews in Ostrowiec, and the community had a beth midrash. During World War I, many Jews left Ostrowiec, and the local community continued to shrink in the postwar period. Following the outbreak of World War II, the town's Jewish population rose again, thanks to the influx of refugees from the western, German-occupied regions of Poland.
German troops occupied the area in June 1941. Ostrowiec, being a railway town, became a mass killing site of Jews, who were brought there by the Nazis from nearby towns. In the fall of 1941, a ghetto was established in Ostrowiec. At the end of that year, the Nazis liquidated it, and all of its inmates, except for several "specialists" and their families, were killed at two sites: in the town itself, and in a forest south of Ostrowiec. The former ghetto was transformed into a labor camp, to which Jews from Worniany, Kiemieliszki, and other nearby towns were brought. In May 1942, there were 102 Jews in the Ostrowiec Ghetto. On April 7, 1943, most of them were shot in the village of Szumsk (present-day Šumskas, Lithuania), ten kilometers west of Ostrowiec. Several individuals, who had been warned by a German officer, were able to flee ahead of the murder operation.
The Red Army liberated Ostrowiec on July 7, 1944.