Mielnik is the oldest documented parish in Podlasie. The local church once housed a miraculous icon of Spas Izbawnik (Christ the Savior and Deliverer). However, it did not survive to this day. It may have burned down during a fire in the wooden church in 1614.
The current church was built in 1821-23. It was damaged during the war in 1941. For some time, it was a Uniate church. After renovation in 2017, the elevation is blue.