The first recorded reference to the parish dates back to 1335. In the fourteenth century, the church was extended and rebuilt in the Gothic style: the nave and the chancel were lengthened, the ceiling was raised and the windows were made higher. The temple owes its present-day appearance to king Casimir the Great who was the founder of the investment. In the fifteenth century a sacristy was added. Side walls of the chancel and the nave, with their rich, stone decor, constitute the elements preserved from the Romanesque church. In 1667 the temple was re-consecrated.
In the early twentieth century the church was enlarged: among others, a chapel and a porch were added, and a sacristy from the south side, whereas the nave was extended towards the west. The Gothic chancel, with its narrow lancet windows and a sculpted eagle of the Piast dynasty on the vault keystone, attracts special attention. The church is oriented, which means the chancel faces the east. In the 60s of the previous century, fragments of the original Romanesque church of the twelfth century were discovered by the north side of the chancel: “blind” arcade with low reliefs depicting mermaids, among others.
The church in Zagość is now the only mark of the first foundation of the Order of St. John in the territory of Poland.