After Jefferson played several years for the basketball team of the University of Arizona, he was selected in the 2001 NBA Draft by the Houston Rockets at the 13th place overall. However, he was transferred through an exchange of draft picks to the New Jersey Nets. Thus, he played his first season for the Nets. In that year he was appointed to the NBA All - Rookie Second Team. In the 2001 /02 and 2002/ 03 season with the Nets, he reached the NBA Finals, where, however, both times terminus. In 2004, he won with the national team of the United States at the Olympic Games bronze medal. In the 2004/ 05 season he started very auspiciously when, after the first 33 games at an average of 22.2 points, 7.3 rebounds and held four assists per game, but he fell for a foul by Chauncey Billups for the remaining 49 games from the regular season. Jefferson laid out in the 2007-08 season his best season when he scored 22.6 points per game. Nevertheless, he was transferred on 26 June 2008 to the Milwaukee Bucks for Yi Jianlian and Bobby Simmons.
After a year in Milwaukee, where he scored 19.6 points per game, he was transferred on 23 June 2009 for Fabricio Oberto, Kurt Thomas and Bruce Bowen of the San Antonio Spurs. For the Spurs, Jefferson was no longer the first or second attack option was still used by the starting small forward for years to come.
On 15 March 2012, he was transferred for Stephen Jackson to Oakland for the Warriors. The Warriors Jefferson could not build on past years. The 2012-13 season he finished with 3.1 points and 1.5 rebounds, which thus was his worst.
On July 10, 2013 he was transferred along with Brandon Rush and Andris Biedrins to the Utah Jazz.
Richard Jefferson is married to fashion model Teresa Lourenco.
His nickname, which he has had a tattoo on his shoulder is RJ.