Designed and built by Father Paul Tay, the Church of the Holy Trinity was officially commissioned by Archbishop Gregory Yong in 1988. At that time, the Singapore government was in the midst of developing new towns all over the country, including Tampines. The Archdiocese had to move in tandem with the development plans as a sizeable Catholic population was forming. Despite a difficult start in conceptualising the building plans, Father Tay's vision for the structural aesthetics and layout of the church soon started to take place, as he also went around door-to-door forming the community for the new church. The ground laying ceremony was done on 8th August 1988 followed by two years of construction.
The Church was officially opened on 30th October 1990 making it the 30th Catholic Church in Singapore. The completed three-storey building was built in the shape of a fish which represents Jesus. The early Christians used the symbol of a fish to identify each other, as the Greek word for fish 'ichthys' became an acrostic for Iesous Christos Theou Yios Soter, or Jesus Christ, Son of God, Saviour. Included in the beautiful building which had its roots in Italian architectural designs and embellishments, the church grounds included a chapel on the ground floor and a kindergarten on the second level. Found throughout the church are also numerous stained glass panels which illustrates the salvation history of the Catholic faith.
As the years progressed, the church's population grew. From the initial 8,000 population, Holy Trinity Church went on to serve some 14,000. Extensive renovations were done in 2006 to accommodate the large crowds. Television and overhead projectors were installed to aid in classroom lessons and meetings.