NBA 09: The Inside is the sequel to NBA 08 where once again the player can partake in a new chapter in "The Life" mode. This time around the player can take control of a created superstar (five total) with the ability to interact with three different characters and constantly change the storyline.

The Team Progression System makes a return, rewarding the player for game exploration and completing certain achievements given to them throughout the game. Completing these tasks can unlock certain accessories that they can use for their created character, showing off their status. Players can also associate with various teammates and coaches, how they act towards these characters will determine their place with the team (being a team player and helping out others will have the coaches play you more and have create a bigger fan base and being a individual loner will alienate them from the team and have a smaller fan base).

The obligatory game modes also exist in this version as well (Franchise, Exhibition) as well as updated NBA rosters with every NBA team available. The Havok engine is introduced for this version, giving the game a more realistic feel when combined with new animations and enhanced character models.

NBA Replay also returns, letting players relive classic moments from the 07/08 as well as partake in the 08/09 season by downloading them off of the Playstation Network (five each week during the season). Players can also upload and share data, show off their created superstars and track their progress through leaderboards and even play against each other in online exhibition games.

Audio commentary is provided by Seattle Supersonics star Kevin Calabro and franchise newcomer Kenny "The Jet" Smith.