Richardson was selected with the ninth pick of the second round in the 2006 NBA D-League Draft by the Fort Worth Flyers. On January 27, 2007, he was signed to a ten-day contract by the Atlanta Hawks. Previously playing for the Flyers, it was the seventh call-up from the D-League during the 2006–07 season. After his second 10-day contract expired, the Hawks opted not to retain him. In March 2007, he was signed to a 10-day contract by the Portland Trail Blazers. At the end of the contract, the Blazers cut him; he played in one game for them. Richardson returned to the Flyers afterwards. Richardson was selected in the first round of the 2007 D-League expansion draft by the Fort Wayne Mad Ants. Richardson spent the 2007-08 NBA preseason with the Miami Heat but was waived on October 29, 2007. On December 20, 2007, he was signed by the Memphis Grizzlies. Until then he was averaging 28.5 points, 6.6 rebounds, 1.8 assists and 1.63 steals in 41.5 minutes in eight games for the Mad Ants. He was named D-League.com Performer of the Week, after averaging 35 points, 6.5 rebounds, and 4.0 assists in two games during the week of December 3, shooting 53.2% from the field, including scoring a league season-high 40 points against the Iowa Energy on November 29. He was waived on January 7, and signed three days later with the San Antonio Spurs. In 2008, Richardson was named MVP of the D-League All Star Game, scoring 22 points on 9/15 shooting. Shortly afterwards, he was signed to another 10-day contract by the Atlanta Hawks. Richardson in the 2008 offseason was signed by the Orlando Magic. On December 8 he received a 3.5 million dollar bonus. In August 2009, he joined the Greek League club Aris Thessaloniki where he averaged 12.2 points and 3.3 rebounds per game. In September 2010 he signed a one-year contract with the Spanish club Power Electronics Valencia. In August 2011, he signed with BC Armia in Georgia. In August 2012, he joined Sidigas Avellino in Italy. In September 2013, he re-signed with Avellino for one more season. In July 2014, he signed a one-year deal with Enel Brindisi. He parted ways with club before the start of the new season, because of personal reasons.
