Joshua Middleton began his career as a comic book artist in 2000 penciling the fantasy title, Meridian, for CrossGen. When he left CrossGen, he worked with a small British indie publisher, Com.X, to produce his creator-owner series Sky Between Branches, but only did a preview issue that appeared in early 2002. It was on this project that Josh began taking his artwork straight from pencils to inks to color himself, foregoing the usual collaborations.
 
Beginning in late 2002, he contributed covers and short stories to X-Men Unlimited. This led to an exclusive contract with Marvel Comics in 2003. He worked as cover artist on the New Mutants and co-created NYX with then-writer Joe Quesada, but left after 4 issues when his Marvel contract ran out. 

He then signed an exclusive with DC in 2004. His first series for DC was the Superman/Shazam: First Thunder mini that debuted in September of 2005. He also was the regular cover artist on the American Virgin series for Vertigo. After that, Josh became the regular cover artist on DC’s Supergirl ongoing series. While no longer under contract with DC, Middleton has continued to produce comic book art almost exclusively for that publisher. 

In addition to his work in comics, Joshua Middleton has illustrated covers for major book publishers, including Scholastic Books, Abrams, Penguin, Viking and Disney Press. He has also served as a conceptual artist/illustrator for feature films produced by Universal, Warner Brothers, Disney, Marvel Studios and Sony.