Elie Horn was born to a Jewish family in Aleppo (then under the French Mandate for Syria). His family emigrated to Brazil when he was 11. As a teenager, he began working with his brother, Joe Horn, in developing the city of São Paulo, gaining experience in real estate. Horn received a degree in law from Mackenzie University. In 1962, he founded his own company, Cyrela, and built it into the largest publicly traded developer of high-end residential buildings in Brazil.
In 2015, Horn and his wife Susy signed Warren Buffett's The Giving Pledge, pledging to donate 60% their wealth over their lifetime to charitable causes. Elie was the first Brazilian to do so.