A blue ensign with the Southern Cross was introduced for ships of the colonial government in 1867 and this soon became a de facto national flag.

The ensign was implemented out of a desire to distinguish New Zealand vessels from those of the Royal Navy and this decision is regarded as an important step in the development of the RNZN.

The New Zealand White Ensign is worn by commissioned RNZN vessels and shore establishments during daylight hours.

The Royal New Zealand Navy (RNZN) was established as a separate force in 1941 but, due to the ongoing Second World War, there was no discussion about granting it a unique ensign.

The RNZN continued to use the British White Ensign including on active service during the 1950–1953 Korean War and the 1948–1960 Malayan Emergency.

[9] This was approved by Elizabeth II and adopted by the New Zealand White Ensign Regulations 1968, an Order in Council made by Governor-General Arthur Porritt on 10 June 1968.

[18] When alongside, anchored or secured to a buoy vessels of the RNZN wear the White Ensign at the stern and the national flag as a jack at the bow.

[19] The White Ensign has been flown from the top of Auckland Harbour Bridge annually on 1 October since 2016 to mark the day the RNZN was founded.

[22][23] In 1971, to commemorate the centenary of the Royal New Zealand Yacht Squadron, its flag officers (the three senior committee members: commodore, vice-commodore and rear-commodore) were granted the right to wear the White Ensign on vessels on which they are skipper; other member's vessels wear the squadron's blue ensign.

The King's colour originally showed a St George's Cross, in line with the Royal Navy White Ensign.