[3][4][5] Alexander was born in the South Bronx, New York City to Julius and Mary Jenkins and cites his mother as the first person to introduce him to fashion.

As of Cycle 14 of the show, Alexander was replaced as a permanent judge on the panel by Vogue editor at large André Leon Talley.

[11] In 2008, the Jays were cast in Operation Fabulous, a show to make over "plain Janes" similar to Queer Eye For The Straight Guy, also produced by Tyra Banks.

[citation needed] On April 20, 2012, Alexander's contract with America's Next Top Model expired alongside photographer turned director Nigel Barker and Jay Manuel.

In May 2020, Alexander and Manuel began a weekly Instagram Live series, later syndicated to Facebook and YouTube, based on their experiences working on the show.

Alexander is also interested in designing and has handmade all his clothes on America’s Next Top Model with the exception of the nurse’s outfit: "I did make the hat and the bag.

[17] In 2010, Alexander wrote Follow the Model: Miss J's Guide to Unleashing Presence, Poise, and Power, which "shares his story and offers tips on how to be more confident".