Smith played college football for Ohio State University, was recognized as an All-American, and won the 2006 Heisman Trophy. He was drafted by the Baltimore Ravens in the fifth round of the 2007 NFL Draft, and has also played for the NFL's San Francisco 49ers. He signed as a free agent with the Pittsburgh Steelers in 2012.

He has advocated for the passage of the FIT Kids Act, federal legislation that would require school districts to report on students' physical activity and to give youngsters health and nutritional information.