The site of the Cathedral Church of St Patrick and St Joseph has been the spiritual centre of Catholicism in Auckland since the early 1840s, and forms part of New Zealand's oldest Catholic cathedral complex. Erected in two stages in 1884-5 and 1906-7, the current Cathedral is a significant example of brick-built Gothic Revival architecture and is the third place of worship to occupy the site.

Located on the Hobson Street ridge, the site was granted in 1841 to pre-eminent Catholic missionary, Bishop Jean Baptiste Pompallier (1801-1871). Pompallier developed the land as a religious base for those of his faith in the new colonial capital, and a complex of religious structures soon emerged. A timber church opened in 1843 to serve the parish of St Patrick and St Joseph, was soon replaced by a scoria church. The latter became a Cathedral upon completion in 1848, when New Zealand was divided into two dioceses. The diocese served by the Cathedral extended south to Taranaki and included what was to become an extensive Maori mission.

Commenced in the early years of the episcopacy of Bishop John Luck (1840-1896), construction of the current Cathedral occurred in two phases. The nave and tower erected in 1884-5 occupied the former site of the convent of the Sisters of Mercy, the first religious order of women in New Zealand (1850). The Cathedral was built by Morris Brothers to the design of Edward Mahoney (1824/5?-1895), the founder of one of Auckland's most prolific and significant architectural practices. The use of brick, subsequently adopted for all Catholic churches designed by Edward Mahoney and Sons, was a significant departure from the timber churches designed by the firm.

The Cathedral was the foremost of three major buildings commissioned by Bishop Luck to accommodate the spiritual and quotidian activities of the diocese. The Gothic-Revival style Cathedral, its associated Presbytery (1888) and Bishop's House (1894) reflect the ideas of eminent British architect Augustus Pugin who was an important influence on nineteenth-century ecclesiastical design. Close personal ties existed between Bishop Luck and the Pugin family.

The Cathedral's steeply-pitched slate roof, external buttressing, lancet-shaped openings and broached spire express Early English style Gothic influences. The central aisle in the nave has rare, locally manufactured cement paving tiles coloured with pigments, currently the only known surviving example of the technology and product.

The practice of Edward Mahoney and Sons was engaged for the second stage of Cathedral construction in 1906-7, Thomas Mahoney (1854/5?-1923) being the probable design architect. The 1848 building which had served as the transept since 1885 was largely demolished and replaced by a new sanctuary and high altar. Sacristies, side chapels and a baptistery were added to the 1880s structure. The completed Cathedral seated 1300 and was dedicated in 1908. The remains of George Michael Lenihan (1858-1910), Bishop of Auckland at the time this work occurred, were subsequently interred inside the Cathedral. St Patrick's was also the resting place of the remains of New Zealand's first Labour Prime Minister Michael Joseph Savage (1872-1940) prior to the completion of his Bastion Point mausoleum in 1943.

An important place of commemoration, celebration and social gathering, the Cathedral was consecrated in 1963 by Archbishop Liston (1881-1976) Auckland's longest-serving bishop. In 1984-5 alterations reflecting the liturgical reforms of Vatican II included removal of the high altar. Works undertaken in 2005-7 included a small chapel addition and the installation of a glass floor panel to reveal the foundations of the 1848 scoria church, a visible reminder of 160 years of Cathedral use on the site. The Cathedral remains a central part of the Catholic mission in Auckland, and is in daily use as a place of worship.

The Cathedral of St Patrick and St Joseph has outstanding historical significance as the site of New Zealand's oldest Catholic cathedral complex and as the centre of the diocese of Bishop Pompallier (1848-1869), founder of the Catholic faith in the colony. It also has special value as the site of the earliest convent of the Sisters of Mercy, the first religious order of women in New Zealand, and for its close associations with the development of the Catholic faith in New Zealand. The place has outstanding spiritual significance for its connections with the country's most populous Catholic diocese and its use as a place of worship since shortly after the foundation of colonial Auckland. It has architectural significance for its Gothic Revival design and as the first place of worship designed in brick by the noted Auckland architectural practice of Edward Mahoney and Sons. The place has aesthetic significance for its ornate appearance, and technological value for its rare nineteenth-century locally manufactured paving tiles. It is socially significant as a place of commemoration and gathering for over 115 years in the current building and more than 165 years on the site.