The three-storey brick building was designed by William Turnbull as a private home for nationally significant collector and bibliophile Alexander Horsburgh Turnbull (1868-1918). Its architecture is a mix of Scottish Baronial, Queen Anne and Medieval architecture.
Businessman Alexander Turnbull became well known as an avid collector of books, paintings, historical letters, maps and artefacts. He began his collection at the age of 17. During his 30s a family inheritance enabled him to expand his collection, which by 1918 grew to become New Zealand's largest private library with over 55,000 items. His Milton, New Zealand and Pacific collections in particular were considered to be of international standing.
Turnbull moved into the house in 1916. The house was designed to store at least 60,000 volumes in its three-roomed library, with living quarters on the eastern side. He was not to enjoy the new home for long, passing away in 1918. His collection was bequeathed to the nation in the hope that it would become the "nucleus of a New Zealand National Collection".
The house, purchased by the government, was opened to the public in 1920 as the Turnbull Library. The Library inevitably outgrew its home as bequests, donations and purchases expanded Turnbull’s collection. In 1973 the Library moved temporarily to a site on the Terrace, before it was moved to its current location within the National Library of New Zealand building.
Turnbull House was threatened with demolition in the 1970s when the Ministry of Works planned an access ramp to link with the motorway. These plans were withdrawn following strong community concern. Since then, the building has had many roles, housing various tenants including community groups, and as a popular location for business meetings, conferences and private functions. Today, nestled amongst the high rise buildings of Lambton Quay and The Terrace, Turnbull House remains an important part of the Government Centre Historic Area.
Comprehensive restoration was undertaken in 1994 by DOC, including re-roofing and restoring architectural features that had been removed, along with ensuring the building is fire resistant. Deemed earthquake-prone by the Wellington City Council in 2009, the building was closed in 2012 pending further strengthening work.