In 2012, he started all 12 regular season games for Ohio State. Against Penn State, Shazier posted 8 tackles, 2 sacks, and an interception in the third quarter that he returned for the game-deciding touchdown. In a victory against Wisconsin, he had 12 tackles, three tackles for a loss, and he made a game-saving tackle on a goal line stand on fourth and inches. He would finish 2012 leading the Big Ten with 17 tackles for a loss and place second in the league with 115 tackles. Shazier also had 5 sacks and 3 forced fumbles for the season.