The Navy had its origins in the Naval Defence Act 1913, and the subsequent acquisition of the cruiser HMS Philomel, which by 1921 had been moored in Auckland as a training ship.

A slow buildup occurred during the interwar period, and then in December 1939 HMS Achilles fought alongside two other Royal Navy cruisers at the Battle of the River Plate against the German ship, Graf Spee.

The first recorded maritime combat activity in New Zealand occurred off the northern tip of the South Island in December 1642.

Māori in war canoes attacked and killed four seamen from Abel Tasman's party, who were at the time in low boats between the main ships.

But the gathering in Parliament in Carl Berendsen's room (including Peter Fraser) could not follow Chamberlain's words because of static on the shortwave and waited until the Admiralty notified the fleet that war had broken out before Cabinet approved the declaration of war (the official telegram from Britain was delayed and arrived just before midnight).

Achilles moved to the Pacific, and was working with the United States Navy (USN) when damaged by a Japanese bomb off New Georgia.

HMNZS Leander escorted the New Zealand Expeditionary Force to the Middle East in 1940 and was then deployed in the Mediterranean, the Red Sea, and the Indian Ocean.

Leander was subjected to air and naval attack from Axis forces, conducted bombardments, and escorted convoys.

They also played an important role in the defence of New Zealand, from German raiders, especially when the threat of invasion from Japan appeared imminent in 1942.

[7] During April 1947 a series of non-violent mutinies occurred amongst the sailors and non-commissioned officers of four RNZN ships and two shore bases.

The resulting manpower shortage forced the RNZN to remove the light cruiser Black Prince, one of their most powerful warships, from service and set the navy's development and expansion back by a decade.

[9] On 3 July these two first ships left Devonport Naval Base, Auckland and joined other Commonwealth forces at Sasebo, Japan, on 2 August.

Further RNZN Loch-class frigates joined these later – Rotoiti, Hawea, Taupo and Kaniere, as well as a number of smaller craft.

Jack Welch, later to become Chief of Naval Staff decades later, wrote that in 1959, the RNZN "was still very much part of the Royal Navy supported by New Zealand tax-payers.

In a security crisis and threat to Malaysia and Sarawak and Brunei, two-thirds of the Royal Navy's operational warships were deployed from 1963 to the end of 1966 with Royalist, Taranaki, and Otago, heavily involved in boarding ships, shore patrols, presence, maintaining the use of seaways and support of the RN's amphibious carriers.

One of the best-known roles that the RNZN played on the world stage was when the frigates Canterbury and Otago were sent by the Labour Government of Norman Kirk to Moruroa Atoll in 1973 to protest against French nuclear testing there.

In May 1982 Prime Minister Rob Muldoon seconded the frigate Canterbury to the Royal Navy for the duration of the Falklands War.

Canterbury was deployed to the Armilla Patrol in the Persian Gulf, to relieve a British frigate for duty in the South Atlantic.

[17] In October 2021 the Defence Force contributed HMNZS Te Kaha to the UK Carrier Strike Group's transit through the South China Sea.

[18] In June 2023, HMNZS Te Mana was confronted by two People's Liberation Army Navy frigates, helicopters, and four other vessels near the disputed Spratly Islands.

[19] In late September 2024 Defence Minister Judith Collins confirmed that HMNZS Aotearoa had sailed through the disputed Taiwan Strait with HMAS Sydney.

[23] Initially, two more frigates were planned, but this was cancelled due to the political pressure surrounding defence expenditure following the New Zealand breakup of military relations with ANZUS in 1986.

In addition, the Patrol Force provides assistance to a range of civilian government agencies, including the Department of Conservation, New Zealand Customs and Police, Ministry of Fisheries and others.

[32] Matataua also provided underwater search and recovery support to the NZ Police,[33][34] and other government and civil agencies as requested and approved through Headquarters Joint Forces New Zealand.

The navy has participated in peace-keeping and peace-making in East Timor, Bougainville and the Solomon Islands, supporting land-based operations.

The 2002 Maritime Forces Review identified a number of roles that other government agencies required the RNZN to undertake.

Roles include patrolling the exclusive economic zone, transport to offshore islands, and support for the New Zealand Customs Service.

[47] All regular force personnel on discharge from the RNZN are liable for service in the Royal New Zealand Naval Reserve.

The primary reserve component of the RNZN is the Royal New Zealand Naval Volunteer Reserve (RNZNVR), which is organised into four units based in Auckland (with a satellite unit at Tauranga), Wellington, Christchurch, and Dunedin: At present civilians can join the RNZNVR in one of three branches: Administration, Sea Service (for service on inshore patrol vessels), and Maritime Trade Organisation (formerly Naval Control of Shipping).

In addition ex-regular force personnel can now join the RNZNVR in their former branch and, depending on time out of the service, rank.