The following lists events that happened during 1823 in New Zealand.

• 7 May – John Kent arrives in Foveaux Strait to investigate the possibility of setting up a flax trade.^[1]
• 16 May – William White and others arrive in the St Michael to reinforce the Wesleyan missionaries in the Bay of Islands.^[2]
• 6 June^[3] – Samuel Leigh and William White establish the first Wesleyan mission at Kaeo, near Whangaroa, which they call 'Wesleydale' (var. Wesley-Dale).^[2][4][5][6]
• 17 July – John Kent on the naval cutter Mermaid visits Otago Harbour and, not knowing it has already been named, calls it Port Oxley.
• 23 June – Phillip Tapsell is married for the first time, to Maria Ringa of Ngā Puhi, by Thomas Kendall. The bride runs away later the same day.^[7][8] This is probably the first Christian wedding in New Zealand (as later claimed by Tapsell himself).
• 3 August – The Brampton arrives at the Bay of Islands. On board are Samuel Marsden, Henry Williams and family, and the Wesleyan missionaries John Hobbs and Nathaniel Turner (and family).^[9][10]
• 9 August – Reverend Marsden, in person, delivers the letter sacking Thomas Kendall from the Church Missionary Society.^[11][12] (see 1822)
• 19 August – After the arrival of John Hobbs and Nathaniel Turner, Samuel Leigh leaves the Kaeo mission.^[4]
• 7 September^[13] – The Brampton runs aground on leaving the Bay of Islands. On board are Samuel Marsden, Thomas Kendall and Samuel Leigh.^[4][12]
• 14 September^[13] – Samuel Marsden and Samuel Leigh resume their departure from New Zealand. Thomas Kendall changes his mind and stays.^[4][12]
• November
  • – John Gare Butler, the original owner of Kemp House, leaves the Kerikeri mission.^[14]

Undated

• The Sealers' War, also known as 'The War of the Shirt', in the Otago region, finally comes to an end (before July). (see also 1810)
• Reverend Marsden starts the third Church Missionary Society mission at Paihia with Henry Williams in charge.^[15]
• The first church in New Zealand is built at Paihia. The original, made of raupo, is not replaced until 1855.^[15]
• John Kent on HMS Elizabeth Henrietta is the first identified European visitor to the Taranaki. Traders and/or whalers had recently visited the area.^[16] Others who visited this year include the barque William Stoveld which is reported to have traded at the Waitara river mouth, and John Guard in the Waterloo.^[17]
• Hongi Hika leads Ngāpuhi in an attack on Te Arawa at Mokoia Island.^[18][19]

• 27 February: (in Scotland) James Hume, medical doctor.
• 9 May (in England): Frederick Weld, 6th Premier of New Zealand.
• 29 June (in Australia): George Clarke, educationalist.^[20]
• 13 August (in Scotland): Thomas Dick, merchant and politician.^[21]
• 17 November (in Tasmania): William Clayton, architect.^[22]

Undated

• Dingley Askham Brittin, politician.^[23]

• History of New Zealand
• List of years in New Zealand
• Military history of New Zealand
• Timeline of New Zealand history
• Timeline of New Zealand's links with Antarctica
• Timeline of the New Zealand environment