Murray will undergo surgery Dec. 22 to repair the tendon in his left leg, Sooners coach Bob Stoops said Tuesday. The championship game is Jan. 8.
"Obviously, we're very disappointed for DeMarco," Stoops said in a statement. "He has been an important part of our success this year and we will miss his contributions."
Murray was Oklahoma's leading rusher before he was injured in the Big 12 title game against Missouri on Dec. 6. The injury was first diagnosed as a bruise, but an MRI exam revealed the damage.
Murray, now the team's second-leading rusher with 1,002 yards, will be replaced by Mossis Madu. Chris Brown leads the Sooners with 1,010 yards.
"With Chris Brown and Mossis Madu, we still have two very fine backs," Stoops said. "Our team has a lot of confidence in their abilities."
Murray also had 395 receiving yards and was second on the team with 18 touchdowns. He will be able to resume training in about five months, said Oklahoma athletic trainer Scott Anderson.
Madu has rushed for 463 yards and six touchdowns as the third-team back. He filled in for Murray during the Big 12 title game and carried 15 times for 114 yards and three touchdowns.