Built in 1119 by Robert De Crevecoeur to replace the earlier Saxon manor of Esledes, the castle became a royal palace for King Edward I of England and his queen, Eleanor of Castile in 1278. Major improvements were made during his time, including the barbican, made up of three parts, each with its own entrance, drawbridge, gateway, and portcullis. The medieval keep is called the "Gloriette" in honour of Queen Eleanor.
In 1321, King Edward II besieged the castle after his queen was refused admission, and used ballistas, or springalds, to force its defenders to surrender. Richard II's first wife, Anne of Bohemia, spent the winter of 1381 at the Castle on her way to be married to the King, and in 1395, King Richard II received the French chronicler Jean Froissart there, as Froissart described in his Chronicles.
Henry VIII transformed the castle for his first wife, Catherine of Aragon, and a painting commemorating his meeting withFrancis I of France still hangs there. His daughter, Queen Elizabeth I was imprisoned in the castle for a time before her coronation.
The castle escaped destruction during the English Civil War because its owners, the Culpeper family, sided with the Parliamentarians. The last private owner of the castle was the Hon. Olive, Lady Baillie, a daughter of Almeric Paget, 1st Baron Queenborough, and his first wife, Pauline Payne Whitney, an American heiress. Lady Baillie bought the castle in 1926. She redecorated the interior, first working with the French architect and designer Armand-Albert Rateau (who also oversaw exterior alterations as well as adding interior features such as a 16th-century-style carved-oak staircase) and then, later, with the Paris decorator Stéphane Boudin. Baillie established the Leeds Castle Foundation. The castle was opened to the public in 1976.