 It was founded in 1591 (according to other sources—in 1596) as the "sloboda" of Novonikolskaya () and later became a fortress.In a 1623 document, the settlement is referred to as the "sloboda" of Osinskaya Nikolskaya (), in 1678—as the "sloboda" of Osinskaya (), in 1732—as the village ("selo") of Osa.It was granted town status in 1739.