This parish dates from the fourteenth century. The original church may have been at Kildrum, through by 1609 there was also a church in Dromore village itself. It was replaced by a 1694 church, which was in turn replaced by a church built in 1846 by the Rev Henry Lucas St George on the site of the present building.
In 1954, one of the walls of this building collapsed during a morning service, although no one was injured the damage was so great that it was decided a new building should be erected.
Holy Trinity Dromore was consecrated by Archbishop Gregg in 1958 at a cost of £28,000. The stone used in the bell tower was brought from the recently demolished Aughentine Castle at Fivemiletown.