| Type: | Cardinal |
| Honorific Prefix: | His Eminence |
| Antonio Tosti | |
| Archivist of the Vatican Secret Archives Librarian of the Vatican Apostolic Library | |
| Church: | Roman Catholic Church |
| Appointed: | 13 January 1860 |
| Term End: | 20 March 1866 |
| Predecessor: | Angelo Mai |
| Successor: | Jean-Baptiste-François Pitra |
| Other Post: | Cardinal-Priest of San Pietro in Montorio (1839–66) Protopriest (1863–66) |
| Cardinal: | 12 February 1838 18 February 1839 |
| Created Cardinal By: | Pope Gregory XVI |
| Rank: | Cardinal-Priest |
| Birth Name: | Antonio Tosti |
| Birth Date: | 4 October 1776 |
| Birth Place: | Rome, Papal States |
| Death Place: | Rome, Papal States |
| Buried: | San Michele a Ripa |
| Parents: | Tommaso Tosti Agnese Massaroti |
Antonio Tosti (4 October 1776 – 20 March 1866) was Catholic Cardinal-Priest of San Pietro in Montorio in Rome and later Camerlengo of the Sacred College of Cardinals and Librarian of the Vatican Library.
Tosti was born on 4 October 1776 in Rome, where he died on 20 March 1866.
Little else is known of Tosti's personal life and few official records exist prior to his elevation to Cardinal (in pectore) and appointment as Cardinal-Priest of San Pietro in Montorio on 18 February 1839 where he served until his death.
In 1859 Tosti was appointed Camerlengo of the Sacred College of Cardinals (not to be confused with the role of Camerlengo of the Holy Roman Church).
Tosti resigned from this post in 1860 upon appointment as the Librarian of the Vatican Library, a title he held until his death in 1866.