How do you say 'made up' in french?

It depends on what "made up" means.

If it refers to the fabrication of a story, i.e. "His whole ghost tale was made up", it would be: "inventé(e)"

If it refers to the application of makeup, i.e. "After three hours he was made up to look like a clown", it would be: "maquillé(e)"

If it refers to a combination of components, i.e. "The wall is made up of bricks", it would be: "constitué(e) de"

If it refers to an arrangement of items in their proper place, i.e. "I made up my room before my parents came over.", it would be: "rangé(e)"