The Hartwell House was first mentioned in the Doomsday Book as belonging to William Peverel, a natural son of William the Conqueror; since that time Hartwell House has played many roles and has a remarkable history. Between 1809 and 1814, during his exile from France, Louis XVIII held his court at Hartwell, signing the constitutional document, confirming his accession to the throne, in the library. Today, portraits of King Louis and his Queen, Marie Josephine de Savoie, hang on the main staircase.

Hartwell House was originally built for the Hampden and Lee families, from whom the Confederate General Robert E. Lee was descended. It remained in the possession of the original families until 1938, when it was purchased by the grandson of Thomas Cook, founder of Cook's Travel Agency.

During the Second World War Hartwell served as an Army billet for the British and American troops. Later, in 1956, it was let to The House of Citizenship, a finish school, which remained in occupation until 1983 when the lease was taken by Historic House Hotels. The resulting restoration, of exemplary tact and sensitivity, has set standards for such work in future.