This cathedral is the mother church of the Episcopal Diocese of Oregon in the United States. It is located in the historic Alphabet District of north-west Portland. It has a progressive Episcopal congregation.

Trinity Episcopal Church was founded on 18th May, 1851 in Portland, Oregon. It was the first Episcopal congregation organised in the then Oregon Territory. The first permanent building was constructed in 1853 and was located on the corner of SW 2nd Avenue and Oak Street. As the congregation continued to grow, a new church was built in 1872 at the new site of SW 6th Avenue and Oak Street. This building was burnt down in 1902 and the congregation decided to relocate again, this time to the fashionable NW 19th Avenue. This new building, which is the current Trinity Episcopal Cathedral, was consecrated on 14th October, 1906.

This current building was built in the Gothic Revival style. The building was redesigned and renovated in the early 1980s. This involved redesigning the chancel and bringing the altar forward to the congregation. On 17th February, 1994 Trinity Episcopal Church was renamed as a cathedral when the Bishop of Oregon relocated the diocesan seat to this location.