He played college basketball for Colorado State University before being selected with the 20th overall pick in the 2007 NBA draft by the Miami Heat.

Smith attended Platte Valley High School in Kersey, Colorado where he was regarded as the state's premier prep player during his senior season in 2003–04.

He was a two-time state player of the year, was named to the All-Colorado team as a junior and senior, was a three-year letterwinner and starter for the Broncos, was named to all-conference and all-state teams three times, and was selected as most outstanding player in state Class 3A tournament as a senior.

[1] As a sophomore in 2005–06, Smith played in and started all 31 games for the Rams, and the season's end, he earned first-team All-Mountain West and second-team NABC all-district honors.

On the season, he averaged 16.2 points on 51.7 percent shooting (178-of-344) with 7.3 rebounds, 2.3 assists and 2.1 blocked shots in 28.7 minutes per game.

[3][4] He left Colorado State ranking ninth on the school's all-time leading scoring list with 1,281 points.

On September 23, 2010, Smith was traded, along with Willie Green, to the New Orleans Hornets in exchange for Darius Songaila and Craig Brackins.

[26] On February 7, 2019, Smith was acquired by the New Orleans Pelicans in a three-team trade involving the Bucks and Detroit Pistons.