The first mention of Osiek dates back to around 1303. From the mid-18th century, the landed estate became the property of the count Sierakowski family h. Ogończyk. The last pre-war owner of Osiek and numerous manors and properties included in the ancestral estate was Count Adam Sierakowski – a social activist and politician. In 1939, the count and his family were murdered by the Nazis. After World War II, the estate was adapted for use as a state farm.
