Coach Brian Kelly made the announcement Monday morning during the Fighting Irish's bowl media day. Martin, a fourth-year junior with a fifth-year option, has started each of the Irish's past 38 games at left tackle and is one of two offensive captains this season.
Nix, a third-year sophomore nose tackle with two years of eligibility remaining, has played in all 25 games the past two years after redshirting in 2010, and he has made 21 starts.
The Jacksonville, Fla., native has been instrumental for the nation's No. 1 scoring defense, recording 45 tackles, 5.5 tackles for loss, two sacks and one forced fumble.
Kelly said that fourth-year junior running back Cierre Wood has not made a decision on his future yet.
He added that reserve freshman tackle Ronnie Stanley will be out for the Jan. 7 Discover BCS National Championship against Alabama after undergoing surgery to repair an issue in his elbow.
Reserve sophomore center Matt Hegarty had a procedure done as well, Kelly said, and is expected to be back in the spring.