The 2009–10 Cleveland Cavaliers season was the 40th season of the franchise in the National Basketball Association (NBA). The Cavaliers finished with the best record in the NBA at 61–21, earning them first place in the East. The season saw LeBron James win the MVP Award for the second straight year. The Cavaliers had the fifth best team offensive rating in the NBA.
After defeating the Derrick Rose-led Chicago Bulls in the first round in five games, the Cavs faced the 4th-seeded Boston Celtics in the Semifinals in a rematch of the 2008 Conference semifinals where the Celtics won in seven games. The Cavaliers were favored to beat them, but lost in six games despite being up 2-1. The Celtics would advance to the NBA Finals and lose to the Los Angeles Lakers in seven games. Following the season, Danny Ferry stepped down as general manager, head coach Mike Brown was fired, and James signed as a free agent with the Miami Heat, but would return to the Cavaliers in 2014, Shaquille O'Neal signed as a free agent with the Boston Celtics, which turned out to be O'Neal's final season as a player, and Zydrunas Ilgauskas also left the team to join one season with the Heat before retiring.
After LeBron's departure, the Cavaliers struggled greatly without him for four seasons, and entered a state of rebuilding. The Cavaliers would not make the playoffs again until 2015, when LeBron returned to the Cavaliers, who drafted All-Star Kyrie Irving and traded for All-Star Kevin Love.
As of 2023, this was the last time that the Cavaliers have won 60 or more games. This was also the last time that LeBron lost in the playoffs before the Finals until 2021 when the Los Angeles Lakers lost to the Phoenix Suns in six games in the first round, which was also the first time in James' career that he exited in the first round.
Key dates
June 25 – The 2009 NBA draft took place in New York City. The Cavs also acquire Shaquille O'Neal, in a trade with the Phoenix Suns. July 8 – The free agency period started. July 13 – The Cavs sign with Anthony Parker. July 19 – Jamario Moon signs with the Cleveland Cavaliers. August 12 – The Cavaliers sign with Leon Powe. October 6 – The Cavs open the Pre-Season, with a victory over the Charlotte Bobcats, in The Q. October 21 – The Cavs close the Pre-Season, losing to the Boston Celtics, in the Value City Arena. October 27 – The Cleveland Cavaliers open the Regular Season, and are defeated by the Boston Celtics, in Quicken Loans Arena. February 17 – The Cavs acquire Antawn Jamison and Sebastian Telfair, in a three-team trade, with the Washington Wizards and the Los Angeles Clippers. March 17 – The Cavaliers clinched the Central Division title for the second straight year, and the third time in franchise history. March 23 – The Cavs waive Darnell Jackson and sign with Žydrūnas Ilgauskas. April 2 – The Cavaliers clinched best record in the Eastern Conference for the second straight year, and the second time in franchise history. April 4 – The Cavaliers clinched the best record in the league, and thus home court advantage throughout the playoffs for the second straight year, and the second time in franchise history. April 14 – The Cavs close the Regular Season, with a loss against the Atlanta Hawks and a 61–21 record. April 17 – The Cleveland Cavaliers open the First Round of the Playoffs, with a 96-83 victory, over the Chicago Bulls, in The Q. April 27 – The Cavaliers close the First Round Series at 4–1, with a 96–94 victory over the Bulls, in The Q. May 1 – The Cavs open the Eastern Conference semifinals, with a 101–93 victory, over the Celtics, in the Quicken Loans Arena. May 13- The Cavaliers lose in the Eastern Conference semifinals, at 4–2 to the underdog Boston Celtics. May 24 – Head Coach Mike Brown was fired.