Alexander attended Concord High School his freshman year and was named to the All-South Piedmont 3A Conference team and earned honorable mention on MaxPreps.com's Freshman All-American Team. He transferred to Northside Christian Academy in Charlotte, North Carolina as a sophomore. As a junior, he moved on to Oak Hill Academy.[1] Alexander scored 50 points in a game as a senior. He averaged 14.1 points per game as a senior, shooting 46.3 percent from behind the arc.[2] He was considered a four-star recruit and was ranked No. 85 in his class by Rivals. Alexander committed to Creighton on October 31, 2015, turning down offers from Clemson, Charlotte and Virginia Tech.[3]
College career
On November 20, 2017, Alexander was named Big East freshman of the week after registering 14 points, three rebounds and two assists in a 92–88 victory over Northwestern.[4] He posted 5.5 points, 2.1 rebounds and 1.8 assists per game as a freshman playing backup to Marcus Foster.[5] In the offseason after his freshman year, Alexander made a point to take 100 shots before bed and work on his shooting technique in order to become Creighton's next great scorer.[6] Alexander scored a career-high 36 points on November 22, 2018, in a 87–82 win against Clemson.[7] He was named Big East player of the week on January 28, 2019, after contributing 26 points, seven rebounds, and four assists in a 91–87 win against Georgetown.[8] As a sophomore, Alexander averaged 15.7 points, 4.0 rebounds and 2.7 assists per game.[9] Alexander was an All-Big East Honorable Mention selection alongside teammate Martin Krampelj.[10] Alexander surpassed the 1,000 point mark in a loss to Georgetown on January 16, 2020, finishing with 14 points.[11] At the conclusion of the regular season, Alexander was named to the First Team All-Big East.[12] As a junior, Alexander averaged 16.9 points, 5.0 rebounds, 2.3 assists, and 1.3 steals per game, finishing second in the Big East in free throw percentage at 86 percent and sixth in the conference at three-point shooting at 39.9 percent.[13] Following the season, he declared for the 2020 NBA draft.[14]
In September 2021, Alexander signed a two-year deal with Virtus Bologna of the Italian Lega Basket Serie A (LBA).[18] On 21 September, the team won its second Supercup, defeating Olimpia Milano 90–84.[19] However, on 15 February 2022, Alexander and the club agreed on ending the contract.[20]