The State of Buenos Aires (Estado de Buenos Ayres) is a secessionist republic resulting from the overthrow of the Argentine Confederation government in the Province of Buenos Aires on September 11, 1852.

The State of Buenos Aires is never recognized by the Confederations; it remains, however, nominally independent under its own government and constitution.

Buenos Aires rejoins the Argentine Confederation after the former's victory at the Battle of Pavón in 1861.