The woman who designed Kiki Iriafen's stunning WNBA draft night dress has seen her pockets grow a little fatter since the ex-USC star rocked the look ... with TMZ Sports learning her business is now surging!

The mind behind the amazing 'fit is Nneka C. Alexander ... and when we spoke with her in the days after Iriafen's gold-and-bronze get-up went viral, she said her DMs have been going crazy.

She told us people have been hitting her up seeking some custom pieces -- similar to the one Iriafen rocked on Monday.

Alexander says the Iriafen dress actually came to life through the hooper's vision of honoring her Nigerian heritage. Alexander was handpicked to bring it to life, and the stunning design came together in just three sketches.

What makes the special moment even sweeter ... Alexander was there on draft night in Manhattan to put the dress on the new Mystics forward.

Iriafen took the stage in the beautiful gown after Washington took her with the fourth overall pick.

The former Trojan -- who averaged 12.2 points and 6.4 rebounds per game in her four-year college basketball career -- called the opportunity a true blessing, and added she can't wait to represent her Nigerian roots in the pros.