The church and the district were mentioned for the first time in 788/90 in the Salzburg register of goods.
At first the church was dedicated to St. Saint Laurentius. Later, on September 8, 1142, Bishop Hartmann von Brixen dedicated it to St. Dedicated to Valentine of Terni. This act of consecration was supplemented on April 9, 1143 by a second consecration by Bishop Hartmann. Researchers took this as an opportunity to assume a "two-storey church". According to this, the consecration of 1142 applied to the basement of the church being renovated, whereas that of 1143 was to the “main floor and thus to be assigned to the completion of the church”.
From about 1140 it belonged as a branch church to the Augustinian monastery of St. Zeno near Reichenhall. From the 14th century it was then a branch church of the parish of Gmain (Großgmain), which was also cared for by St. Zeno. From about 1500 until the time of secularization (1803) the church was the destination of an important pilgrimage to St. Valentine, the patron saint against epilepsy and other diseases. The characteristic offerings to St. Valentine were black chickens locked in a cage behind the altar. Most pilgrims came from today's Flachgau and Rupertiwinkel. The large number of visitors made the church the wealthiest pilgrimage church in the entire area. Therefore, all renovations and the baroque design could be financed from own funds. In the course of secularization, the monastery of St. Zeno was dissolved. Until 1808, the south-east corner of Bavaria (east of the Inn) belonged to the archbishopric of Salzburg, since then to Munich-Freising. St. Valentin was elevated to the status of a parish church in 1809.
In its long history, numerous conversions and structural changes were made to the church until it was as it is today. Thus, in place of the church mentioned in 788/90, a Romanesque new building was built by 1142/43, parts of the nave walls of which are still there. In the 15th century it was rebuilt in the Gothic style, adding the pointed spire tower and a new chancel. The current appearance of the church with its onion dome and baroque façade is the result of baroque renovations in the middle of the 18th century.