I am married under the community property regime. I wish to sell a property that I owned before the marriage and use the entire sale proceeds to purchase a house. Is there a formality I need to comply with to ensure that the house belongs entirely to me?

Yes. Under the community property regime, property acquired during the marriage is, in principle, community property. The notary must include in the purchase deed a declaration of investment or reinvestment of separate funds (déclaration d’emploi ou de remploi de fonds propres) for you to have full ownership of the property (Article 1434 of the French Civil Code).