Raised in the small town of Waituhi, he decided to become a writer as a teenager after being convinced that Māori people were ignored or mischaracterised in literature.

In his novels, plays, short stories and opera librettos, he examines contemporary Māori culture, legends and history, and the impacts of colonisation in New Zealand.

His schoolteacher then instructed his class to read the short story "The Whare" by Pākehā writer Douglas Stewart, about a young man who encounters a Māori settlement.

I said to myself that I was going to write a book about Māori people, not just because it had to be done but because I needed to unpoison the stories already written about Māori; and it would be taught in every school in New Zealand, whether they wanted it or not.After high school, Ihimaera attended the University of Auckland for three years, from 1963 to 1966, but did not complete his degree, and returned to Gisborne where he became a cadet journalist for the Gisborne Herald.

[4] Ihimaera began writing seriously in 1969, around the age of 25, and had his first short story "The Liar" accepted for publication by the New Zealand Listener magazine in May 1970.

[9] His first two novels were published in quick succession: Tangi (1973), which won first prize at the Goodman Fielder Wattie Book Awards in 1974,[10] and Whanau (1974), which told the story of a day in the life of a Māori village.

[2][12] Beginning in 1975, Ihimaera stopped his own creative writing for a ten-year period, due to his belief that it was "tragically out of date" and a wish not to have it seen as the "definitive portrayal of the world of the Maori".

[14] When Ihimaera began writing again, he wrote The Matriarch (1986) which examined the impacts of European colonisation on Māori,[3] and which again received first prize at the Goodman Fielder Wattie Book Awards.

[15] Not long after publication, it came to light that Ihimaera had used passages from the entry on Māori land in An Encyclopaedia of New Zealand (1966), written by Keith Sorrenson, without acknowledgement.

[2][18] In a three-week period Ihimaera wrote his best-known work The Whale Rider (1987), the story of a young girl becoming a leader of her people.

[21] In 1989, he left his job as a diplomat at the Ministry of Foreign Affairs, and the following year he became a lecturer in the English department at the University of Auckland.

In 1993 he received the Katherine Mansfield Memorial Fellowship which allowed him to work in Menton, France, for a period, where he wrote his next two novels: Bulibasha: King of the Gypsies (1994) and Nights in the Gardens of Spain (1996).

[25] It was described in The Dominion Post as "a rollicking good yarn about Maori rural life in the 1950s",[24] and Ihimaera himself has said he was intending to write a Māori Western.

[4][22] The novel was described by scholar Roger Robinson as featuring "conflict, growth and reconciliation, with subplots heroic, political and tragic".

Robinson said it was "no small achievement to take this material off the grubby walls of public toilets, free it from sleaze, write it with vivid passion and through it affirm and celebrate a way of life of which most of us know almost nothing".

[26] In a review for The Dominion Post, Gavin McLean described it as Ihimaera's best book to date, and noted that much of the book's impact came from the intensity of the main character's relationship with his parents and his "desperate need to do better by his children"; "Unlike characters in many similar novels, coming out does not mean discarding all one's past.

[27] In an article in The Sunday Star Times, Ihimaera was quoted as saying the change "was quite a shock to me because I had always tried to hide, to say 'this is a book that could be about "everyman", this is not a specific story'.

[3] Michael O'Leary, writing in the online edition of Landfall, called it an "intriguing and significant, if somewhat flawed, work"; he praised the novel's efforts to tackle the horrific events at Parihaka in the late nineteenth century, and the demonstration of the rich cultural life of Māori in that period, but also noted some issues in the detail of Ihimaera's use of Māori lore and in historical accuracies.

[40][41][42] It was followed by the short-story collection The Thrill of Falling (2012), in which Ihimaera explored a range of genres including contemporary comedy and science fiction.

Written by playwright Nancy Brunning, who died in the same year, the play is a tribute to female characters in Ihimaera's works.

[46] Ihimaera wrote the script for a stage show adaptation of Navigating the Stars, produced by theatre company Taki Rua, which was performed at the Soundshell in the Wellington Botanic Garden in early 2021.

Fox describes his epic novel The Matriarch as "one of the major and most telling 'monuments' of New Zealand's cultural history in the late twentieth century as far as the situation of Māori in this postcolonial society is concerned", noting that Ihimaera "has remained at the forefront of Māori arts and letters to an unprecedented degree, with an impressive output across a range of genres".

[49] As part of the Auckland Arts Festival 2011, musician Charlotte Yates directed and produced the stage project "Ihimaera", featuring Ihimaera's lyrics about his life and works, and with performances by New Zealand musicians including Victoria Girling-Butcher, Paul Ubana Jones, Ruia Aperahama and Horomona Horo.

[52] In the 2004 Queen's Birthday Honours, he was appointed a Distinguished Companion of the New Zealand Order of Merit, for services to literature.

The selection panel described him "as one of New Zealand's most important post-colonial writers, who has consistently proved to be an outstanding storyteller, celebrated as a voice for Māoritanga and a literary leader".