The church is the oldest building in Dolní Počernice - it has been built around 800 years ago. Around 1200, the then owner of the settlement above the river ford of Rokytka decided to build a private stone church near his wooden estate. However, it cannot be ruled out that this stone church could have replaced older wooden church built at the same place. It is unique that this original stone church survived almost entirely in two thirds of the ground plan of current building to this day. The original church had a rectangular apse with a main rectangular nave. The vault above the apse used to be similar to the current vault. The ceiling in the nave was perhaps made with wood beams or perhaps the nave was directly open to a truss.

An inseparable part of the private Romanesque church used to be the western balcony, to which the landlord and his family entered, usually on a wooden footbridge directly from the adjacent estate. While the interior of the church was plastered, painted white and perhaps decorated with paintings, there were numerous gray sandstone blocks built into its outside walls. We no longer know when exactly was the church built. The ancient dedication to the Virgin Mary as well as its simple layout could bear witness to the second half of the twelfth century. It can not be ruled out, however, that it was built a little later with the participation of the building contractors who were carrying out works between 1226 and 1236 for the Prague bishop John II on the church of St. Bartholomew in a nearby village of Kyje.

The original church presumably survived into the fourteenth century, when the neighboring feudal residence was rebuilt into a stone fortress of the high Middle Ages. The nave was then extended to its present ground plan. The reason for doing this was probably an increasing number of settlers and servants. The church was then probably already completely painted white and the new Gothic balcony replaced the Romanesque one.