Ambrosio's parents are Brazilian with Italian and Polish ancestry. They are the owners of a gas station. At age 11, she had plastic surgery to fix her large ears. She later told Tyra Banks on her talk show, "The Tyra Banks Show", that it was a bad experience and she would never do surgery again. She started taking modeling classes at age 12. Two years later she was one of the finalists of the Elite Model Look in Brazil. This launched her modeling career and she signed a contract with Elite Model Management.