Rush averaged 19.8 points per game as a junior, leading the Tigers to the Western Regional finals in the NCAA tournament, where they lost to Oklahoma.

Rush entered the 2002 NBA draft after his junior season and was selected with the 20th pick overall by the Toronto Raptors, who immediately traded his rights to the Los Angeles Lakers.

Rush was projected to be a top 10 pick, but much like what happened to Kareem's elder brother JaRon—a former UCLA star—Kareem slipped down much further than anticipated.

However, due to his three-point shooting accuracy, he would become a more frequently used reserve player in the 2003–2004 playoffs for coach Phil Jackson.

Although the Lakers would lose to the Pistons in the NBA Finals, Rush was able to make somewhat of a name for himself as a sharpshooter, averaging 14 minutes per game and hitting 40% of his three-point shots in the playoffs.

[2] Fourteen games into the 2004–05 season, the Lakers traded Rush to the Charlotte Bobcats for two future second-round draft picks.

In 2017, Rush joined the BIG3 basketball league, playing on a talent-stacked 3 Headed Monsters roster, highlighted by head coach (and NBA Hall of Famer) Gary Payton, as well as Kwame Brown (the first ever directly-from-high-school player to go #1 overall in the NBA draft), Rashard Lewis, Jason Williams, and Mahmoud Abdul-Rauf.

In January 2018, he signed with the Kansas City Tornados of the first-year North American Premier Basketball.