The foundation stone of the Holy Trinity Church was laid on 7 June 1871 by the Bishop of Dunedin who spoke at the event in front of four to five hundred people, and again in the evening at the Masonic Hall. The laying of the foundation stone was the Bishop's first official action in Dunedin. The ceremony took place at about 2 o'clock in the afternoon, and was a well-prepared event: The stone used in the construction of the building was obtained at the Port. The church was designed to hold 220 people, and estimated to cost between £1100 and £1200 to build. In February 1874 the contractor, Mr. Bauchop, who was working towards completing the flooring and roofing, noted that the original plan had been to roof in shingle but that this had been changed to slate both for its durability, and for its better match to the building style. The building was not completed until 28 April 1874, the Bishop of Dunedin on this occasion speaking to a congregation of 300, and congratulating Port Chalmers on its fifth place of worship, but stating, for the record, that of those other four places of worship: "unity would best be accomplished by the return of the Church's erring children to herself". The first minister of the church was the Rev. Mr. Leeson, who had led the congregation at the Masonic Hall at 29 Wickliffe Terrace in the time before the Holy Trinity Church opened. He left in April 1876 for England after a valedictory service on 9 April 1876, in which he noted the difficulty he and his parishioners had faced in building the church: Evidently the association between the Masonic Lodge and Holy Trinity Church was on-going; the Otago Daily Times reporting a Masonic wedding taking place at the church in January 1878. On 14 November 1879 the service of the dedication of the bells of Holy Trinity Church, Port Chalmers, took place. This was the "first chime erected in the Dunedin Diocese". The larger of the two bells had been sent from England three years earlier by the same Rev. Leeson who left in 1876, but had not been raised due to "financial difficulties". By 1879 the church school had a roll of 116 students, with 50 girls and 40 boys in regular attendance. Rev. Lorenzo Moore replaced Leeson and served until 1878, when he was replaced by Rev. Sotham. The Rev. Sotham, from Oxford, England, left to take up a role in Waikouaiti in 1880, and was replaced by Rev. Platts. The Rev. Platts came to the church from Sandridge, Victoria, Australia and was at work in Port Chalmers by May 1880. His family of five arrived on the Arawata on 30 June 1880. One of the Rev. Platts' children was Daisy Elizabeth Platts, who would go on to become Dr. Platts-Mills, one of the first female doctors in New Zealand. On 1 December 1880, there was a fundraising event at the Foresters' Hall in Port Chalmers in order to raise money for a parsonage. The Bishop of Dunedin spoke at the evening and suggested that the main reason for the high turnover of ministers at the church was the lack of a parsonage. He urged the congregation to put aside any "petty feelings" and donate to this worthy cause. Fundraising for the parsonage was evidently successful, as the Otago Daily Times was able to report on 1 November 1881, that a new parsonage had been built on land adjoining the church at the cost of £950. The article also relates that it was the rebuffing of Rev. Lorenzo's offer of money to build a parsonage by the Anglican church that was the cause of that reverend's resignation in 1878. Rev. Platts remained the minister of Holy Trinity Church until shortly before his death on 28 May 1900, after 20 years of service. Bishop Nevill, who had laid the foundation stone of the church, spoke at his funeral.
