Until the 18th century, Kortesjärvi belonged to the parish of Pietarsaari as it was part of the Lappajärvi chapel parish. Any communications with the parish of Pietarsaari were complicated by long distances and a language barrier, with Pietarsaari being a Swedish-speaking region.
The poor transport connections of the period made it difficult to arrange church services, such as funerals. Because of this, the residents of Kortesjärvi felt a stronger connection to the Finnish-speaking Lappajärvi chapel parish.
Before the establishment of the parish of Lappajärvi, Kortesjärvi had joined a couple of other local municipalities to form a chapel community, and in 1789 Kortesjärvi was granted chapel rights. This is deemed to mark the start of the parish of Kortesjärvi.
Church builder Jaakko (Jacob) Rijf from Pietarsaari was selected as the builder of the church. He was a self-taught carpenter who had participated in training exercises in civil architecture arranged by the Royal Academy in Stockholm, which made him the first Finnish craftsman to have received any formal training. In the mid-18th century, when the number of churches being built increased rapidly, the state began to monitor and govern building work, particularly during the rule of Gustav III. For example, the building of separate bell towers was not recommended. The construction of Kortesjärvi Church, completed in 1792, took place during this period, and Rijf designed it in a style typically used for stone churches. Its architecture is typical of the neoclassical Gustavian style. Kortesjärvi Church is an octagonal cross in shape, with a polygonal tower rising from its centre. The tower is topped by a spire, which originally had one bell. About thirty years later, a second smaller bell was acquired for the church.
The church was only consecrated on 9 March 1794, a couple of years after its completion. The delay was likely to be the result of Kortesjärvi not having its own vicar.
As was typical at the time, the church was named after a saint, Katariina (St. Catherine), who was believed to protect cattle.
Kortesjärvi Church is positioned in the traditional style, in an east-west direction, with the altar and vestry located at the eastern end. The pulpit is located in the north-eastern section between the two arms of the cross. The floor area of the church is 423 m2. The church seats about 500 people, including 30 seats on the balcony. The balcony was built in 1909 to house an organ.
It is thought that the pulpit is the handiwork of Jaakko Rijf. It is decorated with several angel’s heads, some of which have been placed in a museum. While several craftsmen have been proposed as the makers of the angel’s heads, it is likely that they were made by artist Eric Cainberg, who was related to Jaakko Rijf.