The Cabinet secretary is formally appointed by the Governor-General by warrant under the Letters Patent Act, on the advice of the prime minister.

This document sets out clear descriptions of the key constitutional conventions observed in New Zealand, and describes the underlying structures, principles and values of government.

[10] This protocol has been largely abided by since, with an only exception occurring at the conclusion of Cecil Jeffery's tenure in 1945 for a period of 24 years[11] when Foss Shanahan assumed the role of Cabinet secretary and held the position until 1955.

[12][13] During this time, the role of clerk of the Executive Council was held briefly by William Harvey[14][15] and then Thomas Sherrard.

[17] When the Prime Minister's Department was established in 1926 then Cabinet Secretary Frank Thomson initially was appointed as its head.

Despite the name, it was not initially a codified practice to have the secretary present at Cabinet meetings, and this was usually at the discretion of the prime minister.

While ministers may remain anonymous in their advocacy or opposition to issues discussed, the Cabinet secretariat would record the agreed action.