Formal:
* Je suis haïtien(ne). (This is the most common and literal translation)
Informal:
* Je suis d'Haïti. (This literally means "I am from Haiti," but it conveys the same meaning)
You can also use the phrase:
* Je suis un(e) Haïtien(ne). (This means "I am a Haitian," but it is a bit more formal than the other options.)
Important:
* Haïtien(ne) is used for both male and female. The feminine form just adds an "e" at the end.
Remember that in French, the adjective (in this case, "haïtien(ne)") usually comes after the noun.