The garden, a typical example of the baroque extension of formal vistas, stretches for 120 ha, partly on hilly terrain. It is also inspired by the park of Versailles. The park starts from the back façade of the palace, flanking a long alley with artificial fountains and cascades. There is a botanical garden, called "The English Garden", in the upper part designed in the 1780s by Carlo Vanvitelli and the German-born botanist, nurseryman, plantsman-designer, John Graefer, trained in London and recommended to Sir William Hamilton by Sir Joseph Banks. It is an early Continental example of an "English garden" in the svelte naturalistic taste of Capability Brown.

The fountains and cascades, each filling a vasca ("basin"), with architecture and hydraulics by Luigi Vanvitelli at intervals along a wide straight canal that runs to the horizon, rivalled those at Peterhof outside St. Petersburg. These include:

The Fountain of Diana and Actaeon (sculptures by Paolo Persico, Brunelli, Pietro Solari);

The Fountain of Venus and Adonis (1770–80);

The Fountain of the Dolphins (1773–80);

The Fountain of Aeolus;

The Fountain of Ceres.

A large population of figures from classical Antiquity were modelled by Gaetano Salomone for the gardens of the Reggia, and executed by large workshops.