The Missouri Flag of Freedom award is given to companies and individuals who are dedicated to helping the state's military veterans.
Nixon said O'Reilly was being honored for hiring veterans under the Show-Me Heroes program.
The Show-Me Heroes program was started three years ago to help connect military veterans with job opportunities when they return home from service.
O'Reilly has three recently-returned military veterans on staff in Springfield.
"If you're looking for an employee who shows up early, stays late, works hard and knows how to overcome adversity, hire a veteran," said Gov. Nixon.
"Those that have fought for our
freedom, represented our country in many ways, you know, deserve to have jobs
when they come back home," said Greg Henslee, O'Reilly Auto Parts
President and CEO. "And we've been proud to be part of that."
O'Reilly has hired more than 500 veterans since January 2013.