Alexander played college football at LSU for four years, but all those wins were vacated after he was determined to be ineligible because his father received embezzled funds from a booster.

In his senior season, the Buford Wolves went 14–1 and finished as GHSA Class AA runner-up, being upset in the state final by Calhoun.

[2] Alexander chose Louisiana State over offers from Alabama, Auburn, Georgia Tech, and South Carolina.

After LSU's 30–27 win over Florida, Alexander earned SEC Offensive Lineman of the Week honors.

[5] Alexander's streak of 32 straight starts snapped, however, when he missed the Arkansas game in week 11 because of a hand injury.

[6] Forgoing the option to enter the 2015 NFL draft, Alexander returned to LSU and was named Preseason First Team All-SEC.

[8] It was reported in June 2019 that Alexander's father, James, received approximately $180,000 from John Paul Funes, an LSU booster convicted in federal court of wire fraud and money laundering after embezzling hundreds of thousands of dollars from his employer, Our Lady of the Lake hospitals.

They said the steep fall in his draft stock likely came from not testing well at the combine and being seen as a prospect who better shows his talents in games.

[20] After having trouble with the Chief's defense during the first three snaps, head coach Jack Del Rio replaced him with veteran Jon Feliciano.

[21] On May 1, 2018, Alexander was suspended the first four games of the regular season for violating the league's policy on performance-enhancing substances.