Mattel Inc. announced last year that it would be selling the doll.
It's part of the Barbie "Shero" line that honors women who break boundaries.
Past dolls have included gymnast Gabby Douglas and "Selma" director Ava DuVernay.
"She's finally here!" Muhammad announced on Twitter this week. "I'm happy to announce that you can now have your very own Ibtihaj Barbie doll starting today!"
The Barbie costs $30.99.
She’s finally here! I’m happy to announce that you can now have your very own Ibtihaj Barbie doll starting today! Available on https://t.co/B93Io3bkKY and https://t.co/MJLAXLM8H4 for $30.99 ⚡️💗 #ibtihajbarbie pic.twitter.com/X4xfcTKcZn— Ibtihaj Muhammad (@IbtihajMuhammad) July 30, 2018
Muhammad graduated from Duke University in 2007.
The Associated Press contributed to this report.