In the last year of his degree, Tredinnick worked part-time as a paralegal for Allen Allen & Hemsley, before accepting a clerkship with Mallesons Stephen Jaques, one of Sydney's leading law firms. Tredinnick worked as a solicitor with Mallesons for a year, before moving into book publishing, where he stayed for nearly a decade; he worked as an editor and publisher at Butterworths, Allen & Unwin and HarperCollins. Tredinnick says of those years: ‘they were part of my education as a writer, of course; I was learning what a sentence was; I was practising grammar and learning about design; I was learning what it took, the years and years sometimes, to make a book and to make it good enough to share.’ Tredinnick left the corporate world and began to write and teach writing (and some courses in leadership and organizational studies in Politics at the University of Sydney). It was from Katoomba and a small apartment in Lavender Bay that Tredinnick wrote and published his first poems and won his first prizes. Tredinnick also travelled North America and worked on his doctoral thesis, a study of nature writing and an attempt to retheorise the capacity of prose to represent landscapes and the more than merely human world—to 'catch the lyric of country', as he puts it. Tredinnick took his doctorate in 2003 and his thesis was published in 2005  Tredinnick's first book, an edited collection of nature writing essays from Australian and North America, "A Place on Earth", came out in 2003 in Australia (2004 in the United States). After that came "The Land's Wild Music" in 2005; "The Little Red Writing Book" in 2006; "The Little Green Grammar Book" in 2008; "Writing Well" (an adaptation of "The Little Red Writing Book" for the international market) also in 2008); "The Blue Plateau" (2009 in Australia; 2010 in the United States); "The Little Black Book of Business Writing" (with Geoff Whyte) in 2010; "Australia's Wild Weather" in 2011. Tredinnick's first collection of poems, "The Road South", appeared as a spoken-word CD in 2008. His first volume of poems was Fire Diary, published in late 2010. That was followed by "The Lyrebird", a chapbook, in 2011 and "Bluewren Cantos" in 2013.