Both sides had previously agreed to a debate in the Rio Grande Valley, but the exact date was in dispute.
The hour-long debate hosted by Nexstar Media Group will be held at the University of Texas Rio Grande Valley.
The O'Rourke campaign is pushing for more town hall-style debates for the two candidates, accepting appearances at four additional debates leading up to election day.
Gov. Abbott's campaign says he will only take part in one debate.
Abbott and his previous Democratic challenger, former Dallas County sheriff Lupe Valdez, only debated once during the 2018 campaign.
Gov. Abbott leads O'Rourke by 7 points according to an August UT Tyler poll.