In 1708 it was founded by a decree of grace from the Archduke of Brunswick and Lüneburg.
As the town belonged to the Kingdom of Hanover, the inhabitants were Protestant Lutheran as subjects. The members of the Reformed denomination have newly arrived fellow citizens from neighbouring North Hesse and Bremen.
The founding of congregations was only permitted under certain conditions. One essential condition was the "inconspicuousness" of the church building, so as not to offend the Lutheran church. For this reason, the building was designed without any external signs of a church but was built in the style of a burgher's house, which blended into the street scene of Burgstraße.
This architectural peculiarity makes the Lutheran-Reformed church in Hann Münden a unique church-historical monument in southern Lower Saxony to this day. The interior architectural style is baroque, and the church has undergone repeated renovations over the centuries. The last and largest renovation took place in 1980/1981. The interior was completely redesigned and the church was given a loosened-up interior design and colour scheme that was adapted to the colours originally used.