The Trinity Church Group comprises four buildings: Trinity Hall (1865), the Schoolroom (1872), Trinity Church (1893) and the Trinity Buildings (1926).

The Trinity Church congregation was established by Henry Trigg, a practising Congregationalist from Gloucestershire, England who arrived in the Swan River Colony in 1829. Trigg initially attended the first Anglican Church where he was a choirmaster. He later joined the Wesleyans, but from 1843 he held prayer meetings in the Congregational tradition in his own home. In 1845 a few friends met to discuss the building of a chapel and 3 pounds was subscribed and a chapel in William Street was built, opening in 1846.

For six years, Trigg conducted all the services until, in 1852, the London Missionary Society sent out the Reverend James Leonard to be the first ordained Congregational minister. In 1863, the congregation decided to build a Church in St George’s Terrace as the premises in William Street were too small. Land was purchased for 350 pounds. The architect of the new Church was Richard Roach Jewell. Jewell had arrived in the Swan River Colony in 1852, to take up the position of Clerk of Works and Superintendent of the Towns of Fremantle and Perth. His first building was the Perth Gaol and Courthouse (1852). By the time he designed the Church for Trigg, Jewell had designed the Pensioner Barracks (1863) at the western end of St George’s Terrace and The Cloisters (1856). Governor Hampden laid the corner stone on 10 May 1864. The Church was built by William Buggin, in 1865, probably with the use of convict labour. The building was constructed out of handmade bricks laid in a Flemish bond pattern. It was a simple building with a timber roof.

In 1872 a hall, also designed by Jewell, measuring 52ft by 28ft and 16ft high and known as the New Schoolroom was built to the rear of the Church. A ceiling was added to the 1865 Church building (Trinity Hall) in 1879.

Henry Trigg died on 15 February 1882. He is memorialised in the central rose stained glass window, donated by his grandson, in the Trinity Church.

In October 1884, the congregation decided to build a commercial building on the Hay Street property. The architect was Henry Trigg (grandson of the deceased Henry Trigg and Perth’s first Australian born architect) and a contract was accepted from Mr Hester to construct the buildings for 1,056 pounds. On 4 August 1892, the proposal was put that a new Church, in front of the existing one, should be built at a proposed cost of 5,100 pounds and the erection of an adjoining suite of offices, to fund the building of the Church was proposed for 2,000 pounds. This was accepted and Trinity Church was dedicated in December 1893 and opened in 1894. The plans and specifications were prepared by Henry Trigg and the contractors were Bunning Brothers at a contract price of 6,100 pounds. The design for the new Church provided accommodation for 750 people on the ground floor and for 100 in the galleries. Additional funds of 500 pounds were budgeted for furnishings and 500 pounds for an organ. The new building was designed so that the Minister’s or speaker’s voice could be heard in every part of it. The Church was to have been seated with chairs, but owing to the slope in the floor, locally crafted pews were substituted. The foundation stone for Trinity Church was laid by His Excellency the Governor on 22 March 1893.

Dr Bevan from the Collins Street Congregational Church, Melbourne came to Perth to conduct the opening services. The ceremony was attended by Sir John and Lady Forrest, Sir James Lee Steere, the Mayor of Perth (Mr A Forrest) and a crowd of the leading citizens of Perth and Fremantle. Sir John Forrest proclaimed that such ‘..a magnificent building would be an ornament to the principal street of the city. Such an undertaking showed that the people were progressing materially and morally and that progress was the order of the day’. The Church also commissioned a two storey office building, Trinity House, adjacent to the new Church and facing St George’s Terrace, at a cost of 1,500 pounds.

In 1900, Trinity Hall was renovated at a cost of 130 pounds. In 1904, a double storey building known as the Guild Rooms, containing a caretakers cottage and gymnasium was constructed at the rear of the office building for 1,637 pounds. Further developments took place at the rear of the place, facing Hay Street in 1923, with the construction of Trinity Buildings and Trinity Arcade.

In 1970, the office building on the eastern side of the site was demolished and, in 1981, a shopping arcade developed, linking Trinity Church with Trinity Buildings in Hay Street and with St George’s Terrace. The redevelopment of the arcade in 1981 provided a range of levels of pedestrian access that run along the eastern side of the Church buildings and provide courtyards and through ways for the public from which they can admire the architecture and avail themselves of the services the Church provides. The redevelopment won the Civic Design Award for 1982-83 for its contribution to the civic amenity of central Perth. The funds received for leasing the site in 1981 permitted restoration of Trinity Hall, the Schoolroom and Trinity Church. Trinity Hall is used as a Church hall and school for senior citizens. The Schoolroom is used as the Trinity lunch room. The work was done in consultation with conservation architect Ron Bodycoat of Duncan, Stephen and Mercer. This is part of an ongoing program of conservation of the place.

Trinity Church has been used as an active centre of worship for over one hundred years. In 1977, the Congregational Church combined with the Methodist and Presbyterian Churches to become the Uniting Church of Australia.