Lee attended Pike High School in Indianapolis and played on their Indiana 4A state championship winning team in 2003.

On April 28, 2009, Lee was hit in the face by Dwight Howard during Game 5 of the Magic's first round playoff series, suffering a fractured sinus.

He then returned for the second round matchup against the Boston Celtics but he was forced to wear a protective mask over his face for the remainder of the postseason.

In Game 2 of the 2009 NBA Finals, Lee missed a potential game-winning layup with 0.6 seconds remaining on the shot-clock at the end of regulation that would have evened the series at 1–1.

After spending his rookie year with the Orlando Magic, Lee was traded on June 25, 2009, along with Rafer Alston and Tony Battie, to the New Jersey Nets for future teammate Vince Carter and Ryan Anderson.

Boston traded Lee and a 2016 second round draft pick to Memphis for in exchange for the Grizzlies' Jerryd Bayless and the Thunder's Ryan Gomes.

[11] On January 14, Lee led Memphis to a 90–87 win over the Oklahoma City Thunder, with a season-high and team-leading 24 points, two of which were win-securing free throws to end the game.

[13] Five days later, he made his debut and first start with the Hornets in a 104–96 win over the Brooklyn Nets, recording five points, one rebound and one assist in 21 minutes.

[16] On January 15, 2018, in a 119–104 win over the Brooklyn Nets, Lee made his 44th straight free throw on a third-quarter technical, tying the Knicks' record set by Chris Duhon in 2008–09.

[17] Two days later, he converted a free throw in the second quarter of the Knicks' 105–99 loss to the Memphis Grizzlies—his 45th straight, setting a franchise record.

[19] On January 31, 2019, Lee was traded, along with Trey Burke, Tim Hardaway Jr. and Kristaps Porziņģis, to the Dallas Mavericks in exchange for DeAndre Jordan, Wesley Matthews, Dennis Smith Jr. and two future first-round draft picks.