The 2005–06 NCAA Division I men's basketball season began on November 6, 2005, progressed through the regular season and conference tournaments and concluded with the 2006 NCAA Division I men's basketball tournament championship game on April 3, 2006, at the RCA Dome in Indianapolis, Indiana. The Florida Gators won their first NCAA national championship with a 73–56 victory over the UCLA Bruins. This was the last Final Four site at the RCA Dome. The Final Four will return to the city of Indianapolis, but will be held at Lucas Oil Stadium.

• Florida won its first national title in basketball, defeating UCLA in the championship game 73–57. The team was led by a group of sophomores, several of whom were the offspring of retired professional athletes, nicknamed "The Oh-fours". Forward Al Horford and guard Taurean Green were the sons of former NBA players (Tito Horford and Sidney Green, respectively), while center and Final Four MOP Joakim Noah was the son of retired tennis pro Yannick Noah. These three (along with fellow sophomore star Corey Brewer) surprised many by choosing not to enter the NBA draft, but instead returning to try to repeat as champions in 2006–07.
• George Mason made an improbable run to the Final Four, becoming the first true mid-major to do so since Penn in 1979. The Patriots' path was not easy, as they defeated schools that had won three of the past six titles—national powers Michigan State, North Carolina and Connecticut—en route to its first Final Four berth.
• JJ Redick of Duke and Adam Morrison of Gonzaga engaged in a year-long battle for the National scoring title and Player of the Year honors. Morrison won the scoring race, edging Redick by 1.3 points per game. However, Redick won most National POY Awards, though he and Morrison were the first co-winners of the 2006 Oscar Robertson Trophy.
• Paul Millsap of Louisiana Tech became the first player ever to lead the Nation in rebounding for three consecutive years.^[2]
• A major realignment of teams in the Big East and ACC sent shock waves across college basketball. Boston College followed Virginia Tech and Miami (who had moved the year before) from the Big East to the ACC. The Big East brought in five teams from Conference USA—Cincinnati, DePaul, Louisville, Marquette and South Florida.
• To replace the teams that defected to the Big East (as well as TCU, who left C-USA for the Mountain West Conference and Charlotte and Saint Louis, who left for the Atlantic 10), Conference USA brought in six new members: Rice, SMU, Tulsa and UTEP from the Western Athletic Conference; Marshall from the Mid-American Conference and Central Florida from the Atlantic Sun Conference.
• Other conference realignments effective this season: The WAC added New Mexico State (from the Sun Belt Conference), Idaho and Utah State (both from the Big West Conference). East Tennessee State moved from the Southern Conference to the Atlantic Sun. The Colonial Athletic Association added Northeastern from the America East Conference and Georgia State from the Atlantic Sun. Troy moved from the Atlantic Sun to the Sun Belt Conference.
• The preseason AP All-American team was named on November 8. JJ Redick of Duke was the leading vote-getter (67 of 72 votes). The rest of the team included Shelden Williams of Duke (63 votes), Dee Brown of Illinois (51), Adam Morrison of Gonzaga (45) and Craig Smith of Boston College (31).^[3]

These schools joined new conferences for the 2005–06 season.