Jackson-Davis attended CenterGrove High School in Greenwood, Indiana. As a junior in 2017–18, he averaged 21.9 points per game, 9.4 rebounds per game, 4.1 blocks per game, and 2.6 assists per game while shooting 67.0 percent from the field; he helped his team to a 20-win season, county and sectional titles and the 4A regional final. In AAU basketball, on the Spiece Indy Heat, he averaged 19.1 points per game, 7.1 rebounds per game, 1.8 assists per game while shooting 59.1% from the field. During his senior season, he led the Trojans to a 21–8 record and a berth in the Class 4A state tournament semifinals. He averaged 21.6 points, 9.3 rebounds, 2.9 blocks, 1.7 assists and 1.0 steals through 29 games. He entered the state semifinals with 1,768 career points. On January 24, 2019, Jackson-Davis was announced as a McDonald's All-American to participate in the 2019 game, where he finished with 7 points, 5 rebounds, and 1 block in 14 minutes.
Recruiting
He was rated as a 4 star recruit by Rivals, 247Sports, Scouts, and ESPN. During his high school career Jackson-Davis was recruited by numerous high-profile schools, including Indiana, Michigan State, UCLA, Ohio State, Purdue, Xavier, among others. On November 30, 2018, Jackson-Davis announced via Twitter that he had committed to attend Indiana after narrowing his choices down to Indiana, Michigan State, and UCLA.
College career
He made his college debut for Indiana with eight points and six rebounds in a 98–65 win over Western Illinois. Jackson-Davis was named Big Ten co-freshman of the week on November 18, after contributing 20 points, eight rebounds and three blocked shots against North Alabama. He was again named conference freshman of the week on December 2 after scoring 21 points and grabbing 11 rebounds in a victory over Louisiana Tech. On February 19, 2020, Jackson-Davis set career-highs with 27 points and 16 rebounds in a 68–56 win over Minnesota. At the close of the regular season, Jackson-Davis was named to the Third Team All-Big Ten by the coaches and media as well as the All-Freshman Team.
Jackson-Davis is the biological son of Karla Jackson and Dale Davis. However, he was raised by his mother and step-father, Raymond Jackson. Originally, Trayce just went by the last name of Davis; however, entering his freshman year of high school, he decided to hyphenate his last name and add on Jackson. He stated, “When I got to high school, I didn’t think it was fair. Ray raised me my whole life, so I did Jackson-Davis. They both want the best out of me, but I would say they do it at different angles." Trayce has two sisters, Caida Davis and Arielle Jackson, as well as a younger brother Tayven Jackson. Tayven was a high school teammate at Center Grove. On March 15, 2019, Jackson-Davis was honored as the Indiana Gatorade Player of the Year. He received the award not only for his athletic abilities, but also for his academic excellence in maintaining a B average, and his exemplary character in which he volunteered locally as a youth basketball coach and at the Wheeler Mission Center in Indianapolis, serving the homeless and those in need.
