He played college basketball for the Cardinals of Wheeling Jesuit University and was the NCAA Division II Player of the Year as a senior in 2018.

In later years, Highsmith played in multiple stints with the Blue Coats, the Crailsheim Merlins of the German Basketball Bundesliga, and is currently on the Miami Heat of the NBA.

His high school coach Brian Hubbard told The Baltimore Sun that Highsmith drew little interest from NCAA Division I colleges.

He averaged 14.5 points and 9.4 rebounds as a sophomore, his first full year as a starter, and was named first team All-Mountain East Conference (MEC).

[16] On July 27, 2021, Highsmith signed with Vanoli Cremona of the Italian Lega Basket Serie A (LBA)[17] with an NBA exit option.

[24][25] On December 20, 2022, Highsmith scored a career-high 18 points, alongside two rebounds, two assists and four steals, in a 113–103 loss to the Chicago Bulls.

[26] The Heat qualified for the play-in tournament and advanced to face the top-seeded Milwaukee Bucks in the first round, whom they defeated in five games in a historic upset.

[27] In game 5 of the Eastern Conference Finals, Highsmith scored a then-playoff career-high 15 points, alongside two rebounds and two steals, in a 110–97 loss to the Boston Celtics.