| Plebiscito delle province venete e di quella di Mantova | |
 Notice of convocation of plebiscite in the city of Treviso | |
 Kingdom of Italy before the plebiscite
Venetian provinces and the province of Mantua
Austrian Empire | |
| Country |  Kingdom of Lombardy–Venetia.svg){kind=small} Kingdom of Italy |
|---|---|
| Region | Provinces of Veneto and Mantua |
| Date | 21 and 22 October 1866 |
| Type | Plebiscite with universal male suffrage |
| Theme | Annexation to the Kingdom of Italy |
| Outcome | Yes: 99,99% No: 0,01% |
| Turnout | 85% of eligible voters |
The Venetian plebiscite of 1866, also known officially as the Plebiscite of Venetian Provinces and Mantua (Italian: Plebiscito di Venezia, delle province venete e di quella di Mantova), was a plebiscite that took place on Sunday 21 and Monday 22 October 1866 to sanction the annexation to the Kingdom of Italy of the lands ceded to France by the Austrian Empire following the Third War of Independence.