Celtic art is a art associated with various people known as Celts; those who spoke the Celtic languages in Europe from pre-history through to the modern period, as well as the art of ancient people whose language is unknown, but where cultural and stylistic similarities suggest they are related to Celts. Perhaps its best known and most influential phase is more correctly known as Insular art of Ireland and Great Britain in the Early Middle Ages, which produced the Book of Kells and other masterpieces. Also covered by the term is the visual art of the Celtic Revival (on the whole more notable for literature) from the 18th century to the modern era, which began as a conscious effort by Modern Celts to express self-identification and nationalism.

Typically, Celtic art is ornamental, avoiding straight lines and only occasionally using symmetry, without the imitation of nature central to the classical tradition, often involving complex symbolism. Celtic art has used a variety of styles and has shown influences from other cultures in their knotwork, spirals, key patterns, lettering, zoomorphics, plant forms and human figures.

Celtic art is a difficult term to define, covering a huge expanse of time, geography and cultures. A case has been made for artistic continuity in Europe from the Bronze Age, and indeed the preceding neolithic, age however the 'celtic' culture is generally considered to arise in the Iron Age at around 1000BC. There are three "traditions" of Celtic art, the first being the continental Iron age art mainly associated with La Tène culture which draws on native, classical and (perhaps via the Mediterranean) oriental sources. The second, Iron Age art in Britain and Ireland, draws on the continental tradition while adding distinctive regional styles. The third, the Celtic "renaissance" of the early Middle Ages in Ireland and parts of Britain, is also called Insular art by those who argue that it arises from a mixture of influences that cannot be characterised as exclusively Celtic. Nevertheless, it was this third tradition formed the basis for the art of the Celtic revival beginning in the late 18th century.

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