The Roman Catholic church of the Benedictine Order in Sremski Karlovci was mentioned in the XVI century.  During the Austro - Turkish war it was destroyed, so in 1702 only the ruins of the old building remained. The Catholic parish was established in 1737 and has had 35 pastors since. Construction of the present church, dedicated to the Holy Trinity, started in 1730 on the site of the former Benedictine cathedral. During the visit of Bishop Paxy in 1763 the building of the church was recorded, as well as the statement that a new roof was installed in 1755. Three altars inside the church are mentioned: The Holy Trinity, The Holy Cross and Mary Help of Christians. The building was completed in 1768 when the church was extended and rebuilt and the parish house was completed. The consecration was attended by Emperor Joseph II himself. Ten years later, the church was visited by the imperial advisor Friedrich Wilhelm Taube. In his travelogue, he states that the building had been recently erected, it was beautiful on the outside and the inside, and that it respectively held a sermon in the German and Illyrian languages.

By order of the Court Council in Vienna in 1783, the craft workshops to the west of the church, as well as the house that was located between the Catholic and Orthodox churches were destroyed. In this way, a view of the western facade of the church of the Holy Trinity from the marketplace and square was made possible. On the ground plan dating to 1842  the dimensions of the Catholic Church and later built-on objects on both sides can be seen, three characteristic buttresses on the east side and two brick turns along the fence with pillars on the west. The church was renovated in 1863 and then in 1924, in 1956 and in 1972. Due to these renovations, it is possible that the present appearance of the church is different from the original to some extent.

The church belonged to the Đakovačka, or Bosnia and Syrmia dioceses, which was created by combining the ancient dioceses of Bosnia and Syrmia, by the bull of Pope Clement XIV 1773. The diocese of Syrmia was established in 1231 by Pope Gregory IX. The seat was in Banoštor, and occasionally in Ilok. In the thirteenth century in Syrmia, a dozen Benedictine abbeys and monasteries were present, until the fall of the country to the Turks. Of 4 archdeaconries and dozens of parishes, only 5-6 survived the Ottoman rule. After the Turks left, the bishops returned to Syrmia, but the seat was situated in Zemun, Petrovaradin or even Kaptol near Požega, far beyond the boundaries of the diocese. With the unification of the Bosnia and Syrmia dioceses, the new Đakovačka diocese included almost 50 parishes. Its seat was in Đakovo. The most famous and prominent among the bishops was Josip Juraj Strossmayer, who was at the head of the diocese for 55 years. In October 2008 the Syrmia diocese was re-established, with the seat in Petrovaradin.
The Roman Catholic Church is a one-nave structure with three-sided apse to the east. It has a barrel vault and is covered with tile. The belfry, with typical baroque cap, rises above the western façade. Since the other facades are mainly covered or hidden by neighboring buildings, the west facade is the most decorative. The base of the facade is a socle, from which rise six shallow pilasters with moulded bases and capitals. The pilasters support an architrave beam and a moulded roof cornice. In the central part of the facade is a pronounced avant-corps crowned with a triangular tympanum. The upper part of the west facade is a gable with typical baroque scrolls, and from it rises the bell tower, which is decorated with pilasters with Ionic capitals.The masonry portion of the bell tower is finished with a moulded cornice. At the height of the bells, four round-arched windows are placed. The baroque cap is rimmed with zinc and at the top is a gilded apple with a cross.
The north and south facades have almost no decoration. They feature semicircular windows and a moulded roof cornice. On the east side of the church is a three-sided sanctuary space with outside support buttresses.
The south-east wall has a walled window with Gothic arches. These architectural elements indicate that it is likely that parts of the former medieval Benedictine church were incorporated into the Baroque church during construction in the eighteenth century.
Inside the church are pronounced double pilasters with moulded bases on the internal socle. The pilasters end in Ionic capitals, above which is a decorative interior arch. The bays are separated by arches and in them are oppositely placed windows glazed with stained glass. There are two bays and the sanctuary area. The floor was paved with stone tiles.
The structural system consists of massive longitudinal load-bearing walls about 100 cm thick. They support round arches, which, in turn, support barrel vaults. The roof structure is wooden. The apse is reinforced by external buttresses.
The Roman Catholic Church of the Holy Trinity is an important architectural monument. It is particularly interesting because of its historical layers which indicate the existence of a religious building in the Middle Ages and the period before the arrival of the Turks in this region. Detailed research could shed light on the history of the building and find out the time of the first Roman Catholic church in that place.