Authenticity in art is manifested in the different ways that a work of art, or an artistic performance, can be considered authentic. The initial distinction is between nominal authenticity and expressive authenticity. In the first sense, nominal authenticity is the correct identification of the author of a work of art; of how closely an actor or an actress interprets a role in a stageplay as written by the playwright; of how well a musician's performance of an artistic composition corresponds to the composer's intention; and how closely an objet d’art conforms to the artistic traditions of its genre. In the second sense, expressive authenticity is how much the work of art possesses inherent authority of and about its subject, and how much of the artist's intent is in the work of art.

For the spectator, the listener, and the viewer, the authenticity of experience is an emotion impossible to recapture beyond the first encounter with the work of art in its original setting. In the cases of sculpture and of painting, the contemporary visitor to a museum encounters the work of art displayed in a simulacrum of the original setting for which the artist created the art. To that end, the museum visitor will see a curated presentation of the work of art as an objet d’art, and might not perceive the aesthetic experience inherent to observing the work of art in its original setting — the intent of the artist.

Artistic authenticity is a requirement for the inscription of an artwork to the World Heritage List of the Educational, Scientific, and Cultural Organisation of the United Nations (UNESCO); the Nara Document on Authenticity (1994) stipulates that artistic authenticity can be expressed through the form and design; the materials and substance; the use and function; the traditions and techniques; the location and setting; and the spirit and feeling of the given work of art.

The authenticity of provenance of an objet d’art is the positive identification of the artist and the place and time of the artwork's origin; thus, art experts determine authenticity of provenance with four tests: (i) verification of the artist's signature on the work of art; (ii) a review of the historical documentation attesting to the history of the artefact; (iii) scientific evidence (x-rays of the canvas, infrared spectroscopy of the paint, dendrochronological analysis of the wood); and (iv) the expert judgement of a connoisseur with a trained eye.

In Sincerity and Authenticity (1972), the literary critic Lionel Trilling said that the question of authenticity of provenance had acquired a profoundly moral dimension, that regardless of the physical condition and appearance, or the quality of workmanship of an artwork, it is greatly important to know whether or not a Ming vase is authentic or a clever art forgery. The preoccupation with the authenticity of provenance of an artwork is historically recent, and particular to Western materialism; in the Eastern world, it is the work of art, itself, which is important; the artist's identity and the provenance of the artwork are secondary considerations.

Consequent to a critically truncated career, the painter Han van Meegeren (1889–1947) earned his living as an art forger, by specifically producing fake paintings of 17th-century artists, such as Frans Hals (1582–1666) and Pieter de Hooch (1629–1684), Gerard ter Borch (1617–1681) and Johannes Vermeer (1632–1675). Van Meegeren produced masterful paintings that deceived critics and art experts, who then accepted and acclaimed the forgeries as genuine masterpieces, especially the Supper at Emmaus (1937) painting accepted as a real Vermeer by experts, such as Abraham Bredius.

To survive the Second World War (1939–1945), van Meegeren dealt forgeries to the Nazi occupiers of the Netherlands (1940–1945). In the post–War reckoning among the nations, the Dutch authorities arrested van Meegeren as a Nazi collaborator who had sold national treasures to the German enemy. To avoid a traitor's death, the painter van Meegeren demonstrated his technical skills as a forger of paintings by the Old Masters, to prove he sold forged paintings to the Nazis.

To guard against unwittingly buying a forged work of art, sellers and buyers use a certificate of authenticity as documentary proof that an artwork is the genuine creation of the artist identified as the author of the work — yet there is much business in counterfeit certificates of authenticity, which determines the monetary value of a work of art. The inauthenticity of forged painting is discovered with documentary evidence from art history and with forensic evidence gleaned from the techniques of art conservation, such as chronological dating, to establish the authenticity of provenance of paintings by the Old Masters. The potential monetary value represented by a certificate of authenticity can prejudice collectors and art dealers to buy recent-period artworks with determined provenance, sometimes established by the artist.