The Kingdom of Sardinia is a state in Europe from the early 14th century until the mid-19th and a predecessor state of the Kingdom of Italy.

A small state with weak institutions when it is acquired by the House of Savoy in 1720, the Savoyards unite their insular and continental domains and build Sardinia—often called Piedmont-Sardinia, or alternatively Kingdom of Savoy in this period—into one of the great powers by the time of the Crimean War (1853–56).

Its final capital is Turin, the center of Savoyard power since the Middle Ages.The kingdom initially consists of the islands of Corsica and Sardinia, sovereignty over both of which is claimed by the Papacy, which granted them as a fief, the regnum Sardiniae et Corsicae ("kingdom of Sardinia and Corsica"), to King James II of Aragon in 1297.

Beginning in 1324, James and his successors conquer the island of Sardinia and established their de jure authority.

In 1420, the last competing claim to the island is bought out.

After the union of the Crown of Aragon with that of Castile, Sardinia becomes a part of the burgeoning Spanish Empire.

In 1720, is ceded by the Habsburg and Bourbon claimants to the Spanish throne to the Duke Victor Amadeus II of Savoy.

The kingdom of Sardinia comes progressively to be identified with the entire domain ruled by the House of Savoy, which includes, besides Savoy and Aosta, dynastic possessions since the 11th century, the Piedmont (a possession built up in the 13th century) and Nice (a possession since 1388).

While the traditional capital of Sardinia and seat of its viceroys is Cagliari, the Piedmontese city of Turin is the de facto capital of the House of Savoy.When the mainland domains of the House of Savoy are occupied and eventually annexed by the Napoleonic France, the King of Sardinia makes his permanent residence on the island for the first time in its history.

The Congress of Vienna (1814–15), which restructures Europe in light of Napoleon's defeat, returns to Savoy its mainland possessions and augments them with Liguria, taken from France.

In 1847–48, in a "perfect fusion", the various Savoyard states are unified under one legal system, with its capital in Turin, and granted a constitution, the Statuto Albertino.

There follows the annexation of Lombardy (1859), the central Italian states and the Two Sicilies (1860), Venetia (1866) and the Papal States (1870).

On 17 March 1861, to more accurately reflect its new geographic extent, the Kingdom of Sardinia changes its name to the Kingdom of Italy, and its capital is eventually moved to Rome.