"We are pleased and happy to be able to add Bill O'Brien to our coaching staff. He has a wealth of experience as both an offensive coordinator and head coach in the NFL and college," head coach Nick Saban said.
"Bill is one of the brightest offensive minds in football, an outstanding teacher and excellent recruiter. He will strengthen our coaching staff and give our players the best possible chance to be successful."
O'Brien arrives after spending seven NFL seasons with the Houston Texans. He is set to replace offensive coordinator Steve Sarkisian, who left for Texas.
The former NFL sideline boss has NCAA experience, posting a 15-9 record with Penn State over two seasons. O'Brien also won Big Ten Coach of the Year honors for his work with the Nittany Lions in 2012.
He will inherit an offense that averaged 48.5 points per game en route to a national championship. The Crimson Tide's offense is expected to look different next season after losing Jaylen Waddle and Mac Jones to the NFL draft, with DeVonta Smith and Najee Harris likely to follow.