Stitt had nearly 69% of the vote in nearly complete results late Tuesday, while Joel Kintsel had about 14%. Mark Sherwood was at about 13%, while Moira McCabe received around 3%.
Meanwhile, State Superintendent Joy Hofmeister easily defeated former state Sen. Connie Johnson to secure the Democratic nomination.
From her watch party in Oklahoma City, Hofmeister said she was humbled and excited to earn the Democratic nomination for governor.
She said she is running a grass-roots campaign whose momentum will carry her into November.