Instead of the normal form letter, Curry responded after speaking to officials at Under Armour to get it changed.
He is also sending her a pair of Curry 5 shoes and the new Curry 6 shoes.
Curry also invited Riley and her dad to a special event scheduled for March 8 to mark International Women's Day, ESPN reported.
UnderArmour addressed the marketing in an email to CBS News, saying, "Thanks to Riley and Stephen, we're correcting a simple yet critical error."
It added a girls section to the Curry line, and the Curry 6 will have co-gendered sizing.