The United Principalities of Moldavia and Wallachia, also known as the Romanian United Principalities, is the official name of Romania following the 1859 election of Alexandru Ioan Cuza as prince or domnitor of both territories.

On 24 January (O.S.)

(5 February) 1862, the Principality of Moldavia and the Principality of Wallachia formally unite to create the United Principalities.

Alongside Transylvania, the principalities become the core of the Romanian nation state.A new constitution comes into effect in 1866 giving the country the official name Romania, and following the establishment of a monarchy, on 14 March (O.S.)

(26 March) 1881, it becomes the Kingdom of Romania.