In 1905, Serbian immigrants to the Pittsburgh area united to form a Serbian Orthodox community. Originally, two churches served the community, both in Pittsburgh's South Side area. St. George Serbian Orthodox Church was located on S. 16th Street and St. Sava Serbian Orthodox Church was on Sidney Street.
In 1962, the two churches were unified into one, and the Holy Trinity Serbian Orthodox Church-School congegration was formed. The full unification took place when Holy Trinity Cathedral, located in Whitehall, was consecrated in 1971.
Within the last several years, the congegration has grown as it welcomed new Serbian immigrants as well as members of St. Mary Serbian Orthodox Church of Clairton and St. Sava Serbian Orthodox Church of Knoxville when those churches closed.
Holy Trinity Cathedral is part of the Serbian Orthodox Diocese of Eastern America, under the leadership of Rt. Rev. Bishop Mitrophan, and the Patriarchate of the Serbian Orthodox Church, located in Belgrade, Serbia.