Moon grew up in Goodwater, Alabama and began playing organized basketball in seventh grade. He attended Central Coosa High School where he played on the junior varsity team as a freshman before playing three years on varsity. As a senior, he led Alabama in scoring with 35 points per game. In the tournament semifinal, he scored 48 points, followed by 50 points in the championship game. Moon earned Alabama Sports Writers Association All-State team honors and went to the Alabama-Mississippi All-Star game. Moon also played on the football team as a senior as a quarterback. He was lightly recruited, as Itawamba Community College was the first school to offer him a scholarship during his senior season, and Moon ended up signing with Northwest Florida State College.
College career
Moon attended Northwest Florida State College for two years. As a freshman, he averaged 4.5 points per game. He averaged 7.7 points per game as a sophomore. Moon was named Sixth Man of the Year as the Raiders finished 33-2 and won the National Junior College Championship. Moon transferred to Morehead State before his junior season, choosing the Eagles because it felt like home. He finished second on the team in scoring as a junior at 10.2 points per game and shot 48 percent from the field. Moon recorded the first triple-double in Morehead State history on December 19, 2016, notching 25 points, 11 assists and 10 rebounds against Central Arkansas. He scored a career-high 26 points against Austin Peay on January 19, 2017. As a senior, Moon led Morehead State in scoring with 16.0 points per game and also averaged 4.6 assists and 3.5 rebounds per game. He was named to the First Team All-Ohio Valley Conference. Moon graduated from Morehead State in May 2017 with a Bachelor's Degree in Exercise Science.
Professional career
On August 10, 2017, Moon signed his first professional contract with ALM Évreux Basket of the LNB Pro B. After six months, Moon left the team due to issues with the coach and returned home to Alabama. His uncle Jamario Moon suggested that he join his team, the Albany Patroons, and Xavier did so after coach Derrick Rowland was impressed with his play. In the Patroon locker room, Xavier became known as "half Moon", in contrast with his uncle, known as "full Moon". Xavier averaged 18 points, 8 rebounds and 6 assists per game and was named North American Premier Basketballrookie of the year. Moon signed with London Lightning of the National Basketball League of Canada on September 7, 2018. He averaged 13.7 points, 4.9 rebounds and 4.1 assists per game in 40 games. Alex Johnson informed Moon of the formation of the Canadian Elite Basketball League, and he joined the Edmonton Stingers. In his first game on May 11, 2019, he scored 36 points in a 118-105 overtime victory against the Niagara River Lions. Moon averaged 19.3 points and 5.7 assists per game for Edmonton and was named league MVP. He led the team to the semifinals before losing to the eventual champions Saskatchewan Rattlers. Following the season, Moon tried out for Raptors 905 of the NBA G League but was one of the final roster cuts. He re-signed with the Lightning on November 15. On January 4, 2020, he scored 39 points in a 113-97 victory over the KW Titans. Moon averaged 21.5 points, 6.5 rebounds and 5.3 assists per game during the shortened 2019-20 season and was named to the First Team All-NBL Canada. On June 25, 2020, Moon signed with Wilki Morskie Szczecin of the Polish Basketball League.
Personal life
Moon is the oldest of three children born to Michelle Moon. Her brother Jamario played professional basketball in the NBA. Moon did not find out who his father, Brian Thomas, was until his junior year of high school. On April 20, 2016, his stepfather Elbert Wilson was murdered while mowing his lawn.
