The 2009 NCAA Division I men's basketball tournament involved 65 teams playing in a single-elimination tournament that determined the National Collegiate Athletic Association (NCAA) Division I men's basketball national champion for the 2008–09 season. The 71st annual edition of the tournament began on March 17, 2009, and concluded with the championship game on April 6 at Ford Field in Detroit, Michigan.

The 2008–09 NCAA Division I men's basketball season began on November 10, 2008, and ended with the 2009 NCAA Division I men's basketball tournament's championship game on April 6, 2009, at Ford Field in Detroit, Michigan. The season saw six different teams achieve the AP #1 ranking during the year. Oklahoma sophomore Blake Griffin was the dominant individual performer, sweeping National Player of the Year honors. The season began with North Carolina becoming the first unanimous preseason #1 team, and ended with the Tar Heels dominating the NCAA tournament en route to their fifth NCAA title. UNC won its six NCAA tournament games by double digits, and by an average of 19.8 points per game. Junior Wayne Ellington was named Final Four Most Outstanding Player.