Walker's medium is wood engraving, predominantly printed graphic novels that tell stories without dialogue. His works are influenced by the styles of Frans Masereel, Lynd Ward and Laurence Hyde, all of whom have produced wordless novels using wood engraving techniques. They are featured in his book Graphic Witness: Four Wordless Graphic Novels. 2010's Book of Hours pays tribute in a series of 99 engraved prints to those who lost their lives on 9-11.The images focus on the workers in the World Trade Center from September 10, 2001, until September 11 at 9:02 am (when the second plane hit). 2012's The Mysterious Death of Tom Thomson tells in a series of 109 prints the story of the events surrounding the mysterious death of Canadian artist Tom Thomson. Walker's 2013 release The Life and Times of Conrad Black is 100 wood engravings that form a wordless biography of the imprisoned former newspaper tycoon Conrad Black.The story traces Black’s life from wayward being student at Upper Canada College through his career, felony conviction, imprisonment and ultimate final release. Walker also produced The Woodcut Artist's Handbook: Techniques and Tools for Relief Printmaking (now in its second printing), a textbook for artists learning woodcut and printmaking techniques. His most recent book is titled 'Written in Wood' and is an anthology of 3 of his wordless narratives including the 9/11 story 'Book of Hours'.