* The Wisdom of Cats (2003)
* The Cat's Meow: A Celebration of the Human-Feline Bond (2004)
* Cat People: Why We Love Them and They Tolerate Us (2005)
* The Joy of Cats: A Collection of Wit, Wisdom, and Purring (2006)
* I Can Has Cheezburger? A Guide for the Internet Age (2007)
* LOLcats: The Book: The Original Book That Inspired the Internet Phenomenon (2008)
* The Purrrfect Cat: A Field Guide to Understanding Your Cat's Unique Personality (2009)
* The Zen of Cats: A Path to Enlightenment Through Feline Meditation (2011)
* The Art of the Cat: Celebrating the Artistry of Cats (2012)
Fiction:
* The Cat's Pyjamas: A Novel of Suspense (2010)
* The Cat Who Came to Christmas (2012)
* The Cat Who Knew Too Much (2014)
Children's books:
* The Cat Who Saved Christmas (2015)
* The Cat Who Found a Home (2017)
* The Cat Who Got Lost (2019)