Straight out of college Zach worked as a CRES support specialist at Credit Suisse. He was a member of the founding team when the service was moved to North Carolina. His duties included booking meetings for high level banking execs, scheduling video conferences, daily QA checks on all videoconference connections, contacting international employees, training new members of the help desk and much more. 
Smithson has been a freelance illustrator at Zach Smithson Illustration since 2009. Over the years he's developed various types of concept art, album covers, promotional posters, corporate logos, costume design, ebook and novel covers, and tattoo design. In 2016 Smithson started as a concept artist for Frontwire Studios, designing video game characters and creatures. 
Issues with Netflix
A piece Zach designed called "Nightmare" appeared to have been copied and painted over on episode 4 of season 2 of "Chilling Adventures of Sabrina " at 44:20 minutes in. Zach was initially distraught because he had applied to major studios before and had been rejected. In his own words: 
So in episode 4 of season 2 of ‘Chilling Adventures of Sabrina ’ at 44:20, they did a paint over of my art. It’d be nice if Netflix at least contacted me about using it. But hey, I’ll be contacting them and in the meantime I’ve got about 5 seconds of Netflix airtime y’all! I’m gonna start an IMDb page. But seriously it kind of sucks that this happens, and has happened more than once with the Sabrina show specifically. All it would have taken is a quick email to ask permission and I would have been able to talk with them. Especially because I have applied to be an artist at companies owned by Warner Brothers before and I was denied, yet they used my art anyway without permission. Hopefully this is sorted out and this kind of thing doesn’t happen to any other artist out there.
After being interviewed by The Daily Dot, Smithson was able to get in touch with a representative from Warner Bros. who explained that the piece was commissioned to another freelance artist. They eventually came to an agreement on compensation and future licensing agreements.