In his freshman season at UTSA, Johnson played in 28 games and averaged 7.7 points and 1.7 rebounds per game, while shooting 38.9% from the field, 42.5% from three-point range, and 86.5% from the free throw line. He subsequently won the Southland Freshman of the Year award. As a sophomore, he played in 34 games (21 starts) and averaged 14.9 points and 3.5 rebounds per game, while shooting 41.7% from the field, 37% from three-point range, and 85.9% from the free throw line. He subsequently earned All-Southland Honorable Mention honors after the season. As a junior, he played in 30 games (22 starts) and averaged 13.1 points, 3.4 rebounds and 1.2 assists per game, while shooting 46.3% from the field, 43.4% from three-point range, and 83.9% from the free throw line. He subsequently earned third-team All-Southland honors after the season.
