[1] Johnson was born in Falkirk, Scotland, and was educated at Duncan of Jordanstone College of Art and Design.

In 2003 Johnson, on assignment for the Detroit Free Press, embedded with the United States Marine Corps for the invasion and early months of the Iraq War.

[2] In 2007, Johnson – writing and drawing for the National Post - traveled with a Canadian International Security Assistance Force in Kandahar, Afghanistan.

Much of that work is now held by the Smithsonian National Museum of American History, in Washington, D.C.[4] In August 2012, Johnson returned to Afghanistan, to observe the US Army ISAF soldiers who took over from Canadian troops in Kandahar, and to Kabul and Masar-e-sharif to observe training missions by Canadian ISAF.

In November 2015, he traveled to Ukraine, as part of the Canadian Forces Artists Program, covering NATO training.