The university said Saturday that the terms of the deal still needed to be approved by its Board of Regents.
Sumlin is 19-5 in two seasons with the Aggies (8-3) heading into their game Saturday at No. 5 Missouri. That's the most victories by a coach in school history in his first two years.
There had been much speculation regarding Sumlin being a candidate to become Southern California's permanent head coach, or that he might be pursued by an NFL team or two as he was after last season. The new deal could put an end to the uncertainty.
"I am humbled and very appreciative of the commitment that Texas A&M has extended not only to me and my family, but to our football program overall," Sumlin said in a statement. "We have only just begun to lay the foundation for sustained, long-term success here at Texas A&M, and we will work hard every day to make this great institution and the 12th Man proud."
In six seasons as a head coach at Houston and Texas A&M, Sumlin has a career record of 54-22.
Coach Sumlin has demonstrated why he is considered among the nation's elite football coaches. His coaching and recruiting abilities are only secondary to his integrity, class and passion for his student-athletes and this University," athletic director Eric Hyman said in a statement. "Texas A&M is making a sincere commitment to Kevin. We are fortunate that he is committed to remain an Aggie for a long time to come, and we are excited about what the future has in store."