Born in Blenheim in 1946, Ian spent the early part of his life living in East Pakistan and England. On returning to New Zealand he attended King's College, Auckland, going on to The University of Auckland, where he gained a MA in English. From 1966 his poems began appearing regularly in journals, including Landfall and Freed. To date, Ian has published 14 collections of poems, six novels, and a collection of short stories, while his prolific essays in art criticism and cultural studies have been collected in How to be nowhere: essays and texts, 1971-1994 and Making Ends Meet:Essays and Talks 1992-2004.

Ian edited The Penguin Book of New Zealand Verse (1985, with Harvey McQueen) and The Penguin Book of Contemporary New Zealand Poetry (1989, with Harvey McQueen and Miriama Evans). He was the General Editor of Ralph Hotere: Black Light, which won the Illustrative Arts section of the 2001 Montana Book Awards, curated and edited Fomison, What Shall We Tell Them? (1994) and Now See Hear! Art, Language and Translation (1990, with Gregory Burke).

Ian won the 1977 Book Award for Fiction for his first novel, Dick Seddon's Great Dive and shared the 1978 NZ Book Award for Poetry for Spells for Coming Out. He was the Burns Fellow in 1972 and his writing has been further recognised by the Writers' Bursary 1974, the Scholarship in Letters 1980, 1989 and the Victoria University writing fellowship 1984, among other awards. He was a member of the Literary Fund Advisory Committee 1977-79 and of the Queen Elizabeth II Visual Arts Panel in 1990. From 1983 to 1990 he was the art critic for The Evening Post and from 1994 to 2004 Ian was Concept Leader Art and Visual Culture at Te Papa. In 2005 he was awarded the Meridian Energy Katherine Mansfield Memorial Fellowship and in the same year published his latest poetry collection Three Regrets and a Hymn to Beauty and Making Ends Meet:Essays and Talks 1992-2004.

Ian was awarded a Fulbright Travel award in 2006, the year he published The Viewing Platform. He was named among the University of Auckland's Distinguished Alumni in 2007 and in the same year received an Arts Foundation Laureate Award.

Ian resumed writing Chinese Opera, a novel he started twenty years previously and then put aside, only to take up again when he discovered a way back into it. Chinese Opera was published in late 2008. In 2009 Ian wrote a monograph on the artist Bill Culbert, Bill Culbert: Making Light Work and a poetry collection Good Business. Both were published by Auckland University Press, and he was honouredwith the University of Auckland Michael King Writer's Residency.

Ian was made an Officer of the Said Order (ONZM) in the 2010 Queens Birthday honours list. Ian moved from Wellington to Auckland in 2011 with his partner Donna Malane, a television writer and producer. In the same year, Victoria University Press published his novel The Catastrophe. He was the New Zealand Poet Laureate from 2011-2013 and over this same period was an adjunct Senior Lecturer at the University of Auckland.

Ian is the 2013-14 Creative New Zealand Writer in Residence-in-Berlin.