He was born into the noble Kossakowski family of the Ślepowron coat of arms, using the Korwin cognomen.

His father was Jan Mikołaj Kossakowski, a stolnik of Kaunas, and his mother was Anna, née Skorulska.

[2] He was regarded as a good and progressive landowner, commissioning numerous drainage works that improved and expanded the land he owned.

Between his own estates and those of his wife's family, he founded a town, which he named Janów in honor of his father (today Jonava, in Lithuania).

[4] His only daughter, Anna, married Karol Czarniecki, the son of the castellan of Bracław, Jan Antoni.