Archaeological findings document a Slavic settlement in Plazy in the period of the 10th or 11th century. The local name of "Pod tvrzí" suggests the presence of the later medieval fortress which was located on the northern side of the village. While excavating the water reservoir, the ruins of a wooden building were discovered, to which a wide pebble road led. According to the position of the site, we can assume the existence of a water fortress, e.g. a fortress with a ditch filled with water. The fortress in Plazy was the seat of Václav of Plazy — a robber who was taken to Court by Vok of Rotštejn (litigation concerned the case of property theft said to have occurred in 1322). The records of that year are important for another reason too. They are the oldest surviving written mention of the village of Plazy.

The oldest written mention of the Church is linked to 139, when it was the Parish Church. During the Hussite Wars, the Church became Calixtine. The practice of Sub Utraque Specie was maintained here until the 18th century. In 1525, the Council of Mladá Boleslav bought the estate of Volenovice from Markvart Fryček of Daliměřice, including the Church in Plazy. The Church came under the administration of the Boleslav Deanery and again became a Parish Church in 1878.

The Church was significantly damaged during the Thirty Years' War. A 1660 report states that it was destroyed at that time. It also lost its vaulting and therefore could not be used for its original purpose. The new tower was built in 1731. However, it collapsed  shortly after completion, damaging the Church itself.

Construction of the new Church began in 1739, according to plans of the Boleslav architect, František Bossi. The main altar and the central image of St. Simon and St. Jude were painted by Josef Ruta. Woodcarvings come from the workshop of Boleslav woodcarver, František Prášek. The total cost of the Church construction extended to the considerable sum of 3 500 guilders.