The Class of 2019 quarterback, a three-star prospect, is originally from Hawaii. He and his family moved to Alabaster, Alabama, and began playing at Thompson High School shortly after Tua enrolled at Alabama last year.
"Alabama is where I feel most at home," Taulia told ESPN's Tom VanHaaren via text message Saturday. "It's close to home and my family. Family is the biggest thing to me.
"It's going to be fun. We get to go to school together and room together, too. I know my family would love that, so I'm happy we get to play together."
Tua served as Jalen Hurts' backup as a true freshman last season until Hurts was benched during halftime of the national championship game. Tua came on and helped orchestrate the come-from-behind victory with three passing touchdowns, including the game-winner in overtime.
Tua and Hurts have been battling for the starting position this spring.
Taulia held offers from Florida, Ole Miss, Michigan and Tennessee, among others.
"I want to be my own person and do my own thing," Taulia told ESPN before his commitment. "I've always seen my brother as the best quarterback, the best runner. So every time I do things, I try to compete with him and try to do better than him.
"When I talk to coaches, I tell them I want to be my own person, and I just try to control what I can control and show it on the field."