Formal:
* Je suis français(e). (I am French) - This is the most common and formal way to say it. You use "français" for a male and "française" for a female.
Informal:
* Je viens de France. (I come from France) - This is a more informal and literal translation of "I am from France."
* Je suis originaire de France. (I am originally from France) - This emphasizes that you were born or raised in France.
Other variations:
* J'habite en France. (I live in France) - This implies that you currently reside in France.
* Je suis né(e) en France. (I was born in France) - This is specific to your birthplace.
Choose the phrase that best suits your situation and the level of formality required.