NBA 2K9 is a basketball simulation video game developed by Visual Concepts and published by 2K Sports. It is the tenth installment in the NBA 2K franchise and the successor to NBA 2K8. It was released in October 2008 for Microsoft Windows, Xbox 360, PlayStation 2, and PlayStation 3. Kevin Garnett is the cover athlete of the game. NBA 2K9 is the predecessor to NBA 2K10 in the NBA 2K series.

Like past games in the series, NBA 2K9 simulates the experience of the sport of basketball, and more specifically, the National Basketball Association. Players play NBA games with any team of their choosing, and may customize many different aspects to alter the play style and overall presentation. Several single- and multiplayer game modes are present, including season, online, and quick play, as well as the ability to create new teams and players.

NBA 2K9 received positive reviews from critics upon release. Most positive comments were concerning the overall gameplay, and the aesthetical presentation, some called NBA 2K9 the "best basketball game around". Some criticism was directed at the game for what some saw as having a lack of new features. By July 2009, the game had sold over 2 million copies.