Zy Alexander attended Loreauville High School in Louisiana, where he played three positions on the football team (quarterback, wide receiver and free safety). He also played on the baseball team and was the leadoff hitter and played outfield. Alexander was not a ranked prospect and committed to play college football for the Southeastern Louisiana Lions.
In his freshman season at Southeastern Louisiana, he was named first team All-Southland Conference after playing 13 games and leading the league in interceptions with six. In 2022, he earned First-Team All-Southland Conference for the second straight year. He started all 13 games and finished with 27 tackles, three interceptions, and four pass breakups. After the conclusion of the 2022 season, Alexander decided to enter his name into the NCAA transfer portal and decided to play for the LSU Tigers.
The junior cornerback started the first eight games before suffering season-ending injury just before halftime vs. Army. Prior to that, he had developed into LSU's top cover cornerback, recording 44 tackles, seven pass breakups and two interceptions.