The 2003 Tostitos Fiesta Bowl was a college football bowl game that was the designated Bowl Championship Series (BCS) National Championship Game for the 2002 NCAA Division I-A football season, taking place on January 3, 2003 at Sun Devil Stadium in Tempe, Arizona. The Ohio State Buckeyes, co-champions of the Big Ten Conference, defeated the heavily favored Miami Hurricanes, defending national champions and champions of the Big East Conference, in double overtime by a final score of 31 - 24. The game was only the second overtime result in either the BCS or its predecessors, the Bowl Alliance and Bowl Coalition, following the 2000 Orange Bowl between the Alabama Crimson Tide and the Michigan Wolverines. By virtue of their victory, Ohio State won its first consensus national title since 1968 and became the first team in college football history to finish a season with a 14-0 record.

The Bowl Championship Series (BCS) was a selection system that created four or five bowl game match-ups involving eight or ten of the top ranked teams in the NCAA Division I Football Bowl Subdivision (FBS) of American college football, including an opportunity for the top two teams to compete in the BCS National Championship Game. The system was in place for the 1998 through 2013 seasons and in 2014 was replaced by the College Football Playoff.