In May 2001, Johnston was one of the three founding editors of NinthArt.com, an attempt at taking a literary and critical approach to the comics medium designed to act as a journal and aimed at "the discerning reader".

[5] Between 2001 and 2004, he contributed a mostly-monthly editorial entitled "Cassandra Complex",[6] and for five years formed one-third of the infrequent "Triple A" discussions, including the last (on 19 June 2006).

[12] After this initial mini-series, Johnston penned a number of graphic novels for Oni Press – Spooked (with Sophie Campbell), Julius (with Brett Weldele) and Closer (with Mike Norton) released between February and May 2004; The Long Haul (with Eduardo Barreto) and F-Stop (with Matthew Loux) released in February and April 2005.

Starring Charlize Theron and directed by David Leitch,[16] the film, retitled Atomic Blonde, premiered in March 2017 at the South by Southwest festival.

[citation needed] Johnston began publishing a series of spy thriller novels about elite MI6 hacker Brigitte Sharp in 2017.

[24][25] In 2008 Johnston wrote the script for the video game Dead Space[26] as well as a comic book prequel to the Electronic Arts videogame.

In 2013 Johnston began publishing with Image Comics,[27] starting with the "dark fantasy" Umbral in November 2013,[28] and sci-fi/crime series The Fuse in February 2014.

[37] Johnston's 2001 novel Frightening Curves won the 2002 American Independent Publishing (IPPY) "Best Horror" award at Book Expo America.