Jeziorko [jɛˈʑɔrkɔ] is a village in the administrative district of Gmina Piątnica, within Łomża County, Podlaskie Voivodeship, in north-eastern Poland.

In 1807 it was regained by Poles and included within the newly established but short-lived Duchy of Warsaw, and in 1815 it passed to the Russian Partition of Poland.

[3] After the joint German-Soviet invasion of Poland, which started World War II, the village was occupied by the Soviet Union from 1939 to 1941, and then by Nazi Germany from 1941 to 1944.

Owner of the Jeziorko manor, Wacław Schirmer, was arrested and deported to forced labour by the Soviets in 1939, and probably later murdered in 1941, while his family managed to escape and hide in Warsaw in the German-occupied part of Poland.

Stanisław Marchewka [pl] (1908–1957), notable member of the local Polish resistance movement in World War II, was born and lived in the village.