Sources told ESPN and The Athletic earlier this week that the Tide planned to hire O'Brien in the next few days. Alabama coach Nick Saban confirmed that O'Brien will join the team during a radio appearance Wednesday on SportsRadio 610.
O'Brien was in Tuscaloosa, Ala., on Wednesday for his second visit to the Alabama campus.
"I think he's an outstanding coach and a really good person," Saban told SportsRadio 610. "He's got a good family and I think he'll do a good job with our players here.
"I've always tried to have the best knowledge and experience I can for our players and their development, and I certainly think he can contribute to that in a very positive way."
The Texans fired O'Brien as their general manager and coach on Oct. 5, after an 0-4 start to the 2020 season. O'Brien had coached the Texans since 2014.
He had a 52-48 record in seven seasons with the AFC South franchise. The Texans went 11-5 in 2018 and 10-6 in 2019. O'Brien reached the playoffs four times.
O'Brien will replace former Alabama offensive coordinator Steve Sarkisian, who left the job after Monday's College Football Playoff National Championship game to become the head coach at Texas.
O'Brien worked as an offensive position coach and offensive coordinator at Brown, Georgia Tech, Maryland and Duke before he entered the NFL ranks in 2007 as an offensive assistant for the New England Patriots. He also served as head coach at Penn State in 2014 and 2015.
Saban on Wednesday also was named the winner of the 2020 Paul "Bear" Bryant Coach of the Year Award. The Crimson Tide have a 79-6 record with three national titles over the last six seasons.