Damien is the author of thirteen books, including the novels The Miserables, which won the New Zealand Book Award for fiction in 1994 and Nineteen Widows Under Ash, which was joint runner up for the Deutz Prize for Fiction in the 2001 Montana New Zealand Book Awards. His novel The Fainter was runner-up for the Montana Medal for Fiction in 2007 and was shortlisted for the Commonwealth Writers’ Prize. He received a Whiting Writers’ Award from the Whiting Foundation, New York, in 1992, and his novels have been long-listed three times on the International IMPAC Dublin Literary Award.

His essay-length book When Famous People Come to Town appeared in 2002. He has also published two books of stories, The Veteran Perils and for everyone concerned, and a book of poems, The Idles. His television scriptwriting includes work on Duggan and The Insiders Guide to Happiness. His first play, Drinking Games, was produced at Circa Theatre in 2008.

He holds an MFA from Washington University, has worked in publishing and was a founding editor of Sport. In 2005 the anthology he edited, Great Sporting Moments, won a Montana Book Award.

In 2008 Damien was awarded the Katherine Mansfield Fellowship. His sixth novel, Somebody Loves Us All, was written during his time in Menton and published by Victoria University Press in 2009.

As a musician and songwriter, in 2011 he released an album of original material ('Group Hug') under the name The Close Readers; followed up by 'New Spirit' in 2012 and 'The Lines Are Open' (2014). His most recent publications as a co-editor are The Best of the Best New Zealand Poems, and The Exercise Book: Creative Writing Exercises from Victoria University of Wellington’s International Institute of Modern Letters.

In 2013 Damien received an Arts Foundation Laureate Award.

His 2014 inaugural lecture, 'No Hugging, Some Learning: Writing and Personal Change', can be viewed online.

Max Gate (VUP, 2013), a novel about Thomas Hardy, was a fiction finalist in the 2014 New Zealand Post Book Awards. The book was published in the UK and US by Aardvark Bureau in mid-2016. In 2015 Damien was a guest writer at the Adelaide Writers' Week and also at WordFest in Calgary and at the Vancouver Writers Festival. His novel, Dad Art (VUP 2016), was launched at the 2016 New Zealand Festival. And another novel Lifting was published by VUP in 2017.

Damien's first young adult novel, Aspiring (Massey University Press, 2020) won the Young Adult section in the 2020 New Zealand Book Awards for Children and Young Adults.

Damien's novel Delirious (Te Herenga Waka University Press) was released in October 2024.