The Garrison Church, also known as Holy Trinity in Millers Point, Sydney was the first military church built in colonial Australia. It continues as an active Anglican church, now in a joint parish with St Philip's Church, part of the Diocese of Sydney.
The church is located at the north end of Fort Street, and is surrounded by houses and terraces from the Georgian and Victorian periods.
On 1 November 2013 the Garrison Church merged with St Philip's Church to form a joint parish using both buildings for combined ministry.
The Garrison Church was planned at a meeting convened by Reverend William Cowper in December 1839 because the seating capacity at the nearby St Philip's Church had been outgrown by the congregation. Cowper made a significant contribution to funding the church, stipulating that it be named "The Holy Trinity". The land was granted for the church and associated schoolhouse by George Gipps. The foundation stone was laid by Bishop William Broughton on 23 June 1840. At the foundation service the Sydney Morning Herald reported that Broughton concluded his address "expressing his belief that those present would not only avail themselves of the building about to be erected for perpetuating the true worship of the true God, but also expressing his fervent wishes that the building might for generations be devoted to the purposes for which it was to be constructed." The Garrison Church was one of nine or ten churches under construction at the time, projects considered by the Sydney Morning Herald at the time to "clearly prove ... still Religion and Morality are rapidly advancing amongst us".
This Foundation stone of a Church in Honour of the Holy Trinity, erected with the aid of Her Majesty's Government, by the Inhabitants of the Parish of Saint Phillip in the Town of Sydney, and Colony of New South Wales, was laid by the Right Reverend Father in God, William, Lord Bishop of Australia, on the XXIII Day of June, in the year of our Lord MDCCCXL, the IV year of the Reign of Queen Victoria, and the LIII of the Colony, Sir George Gipps, Knight, being Governor. The Bishop of Australia, Trustee; the Rev William Cowper, chaplain of St Phillips, Major George Barney, commanding Royal Engineers, Robert Campbell junior, merchant, acting Committee for the Building.