It seems as if the French have a different word for everything and the French Happy Birthday song is no different. Here are the lyrics to the French Happy Birthday song. Remember to sing loudly.
Other French that you may want or need:
birthday un anniversaire
birthday cake un gâteau d'anniversaire
birthday card une carte d'anniversaire
birthday party une fête/soirée pour son anniversaire
birthday present un cadeau d'anniversaire
When is your birthday? Quelle est la date / Quel est le jour de ton anniversaire ?
What did you get for your birthday? Qu'est-ce que tu as eu pour ton anniversaire ?
If you are walking down the street in Paris and you are asked: "is today your birthday?" say "Oui."