While at St. Edward, Williams played limited time as a freshman on a team anchored by Sam Clancy, Jr. and Steve Logan that went on to win the OHSAA state title. During his later years in high school, he was named first team All-Ohio and named to numerous All-American teams. He was named AP and Gatorade Player of the Year for Ohio and played in the McDonald's All-American Game.
Williams was not selected in the 2005 NBA draft. However, he was signed as a free agent by the Los Angeles Clippers of the NBA during the 2006-07 season. He appeared in four preseason games for the Clippers, starting one, but did not make the final roster. After playing in Spain, Japan and Israel, Williams joined the Cleveland Cavaliers' summer league team in July, 2008 and made the team's training camp roster. On October 23, the Cavs waived veteran guard Ronald Dupree, and Williams became a full-fledged member of an NBA team for the first time in his career. His contract was nonguaranteed until January 10, 2009, after which time the contract would have been guaranteed. Williams played in his first regular season NBA game and scored his first points on December 12, 2008, against the Philadelphia 76ers. Williams became the sixth member of North Carolina's 2005 National Championship team to play in the NBA, joining Rashad McCants, Sean May, Raymond Felton, Marvin Williams, and David Noel. Williams was waived by the Cavs on January 7, 2009. Five days after being released from the Cavs he re-signed with the team with a 10-day contract. He was released on February 2 after his second 10-day contract expired. He then joined the D-League with Rio Grande Valley Vipers on February 14. On April 8, he was re-signed to a contract for the rest of the season. On February 9, 2010, Williams put up a career high in points with 17 to go along with 3 rebounds, 2 assists, and 1 steal in 28 minutes of play. In the 2010 offseason, Jawad signed to play with the Cavs for the 2010–11 NBA season. On December 27, 2010, Williams was again waived by the Cavs. In February 2011, he signed with Hapoel Jerusalem in Israel. For the 2011–12 season, Williams signed with Paris-Levallois Basket in France, rejoining college teammate David Noel. Williams stayed with Paris-Levallois for the 2012–13 season, but while Noel left Williams was joined by former college teammate Sean May. Paris-Levallois waived him on January 15, 2014. In February 2014, he signed with Pınar Karşıyaka of Turkey for the rest of the 2013–14 season. On June 13, 2016, Williams signed with AEK Athens in Greece for the 2016–17 season. On February 12, 2017, he parted ways with AEK. The next day, he signed with Italian club Pallacanestro Reggiana for the rest of the season. In July 2017, Williams signed with Alvark Tokyo of the Japanese B.League.
