Georgia Tech went 4-4 with Key as the interim coach as he took over a program that started the season 1-3 under Geoff Collins, who went 10-28 with the Yellow Jackets before being fired Sept. 26.
Key is a former team captain and All-ACC offensive lineman at Tech, starting 44 games from 1997 to 2000. He returned to his alma mater as an assistant coach in 2019 and has served as the assistant head coach, run game coordinator and offensive line coach before becoming the interim head coach.
"I am so proud and grateful to be the head coach at my alma mater, Georgia Tech," Key said in a statement. "Like I've said many times over the past two months, I love this team, and I couldn't be more excited to be their head coach. We will work unbelievably hard to make our fans, alumni and former players very proud of this program."
Key is the first hire for new athletic director J Batt, who came from Alabama to help revive Tech's athletic department, which has struggled financially and athletically in recent seasons.
"Since I arrived on campus earlier this fall, I have observed first-hand Coach Key's leadership, passion, energy and genuine care for our student-athletes, our football program and the Institute, as well as how his players and staff responded to his leadership and the genuine care that they have for him," Batt said in a statement. "There was strong interest from across the country to be the next head coach at Georgia Tech, and we conducted an exhaustive national search. At the beginning and end of the search, it was clear that the best choice for Georgia Tech is Brent Key.
The school interviewed 10 to 12 candidates, including Tulane coach Willie Fritz, sources told ESPN.
Tech struggled to lure a big outside name because of the school's reluctance to guarantee large portions of the contract, with the amount of guaranteed money a nonstarter for some candidates.
The school owes Collins more than $11 million, and financial concerns are significant.