The parish in Okonin was probably founded by the Teutonic Knights in 1325. The church was built in the middle XIV century. During the First Swedish War in 1626-1629, the church was destroyed. It was rebuilt around 1640 thanks to the foundation of Jan Działyński, the starost of Pokrzywno. The present call of St. Cosma and Damian only became established in the 17th century. During the works in 1841, the tower was raised, and in the years 1911-1913 a thorough renovation of the temple was carried out, adding a new sacristy and partly revealing the gothic polychrome. Subsequent conservation works were carried out at the temple in 1990-1996.
The church is a gothic, brick building on a stone plinth, aisleless, buttressed, it has a massive, three-story tower from the north. In its ground floor there is a former sacristy. In the thickness of the tower walls there are stairs leading to the attic. Window openings with a pointed arches are mostly enlarged. The eastern and western gables were built in the 17th century. Inside, it is worth seeing gothic wall paintings from around 1390.