Gaddie has served as an attorney in Northwest Missouri for 15 years.
He said Division Six holds a special place in his heart. He had his first jury trial in that courtroom before graduating from law school.
Gaddie said he is excited for a chance to serve his hometown in a different way.
"The associate handles both criminal and civil cases, and I have a background as both a criminal prosecutor, a criminal defense lawyer, and also, I've represented clients on both sides of civil cases," said Gaddie.
Gaddie will run as a Democrat.
The primary election is August 5.