Other religions that owe much to Celtic spirituality are Wicca and its neopagan offshoots. While Wicca is of course not a Celtic religion, the influence of Celtic ideas and romantic druidry can clearly be seen in much of its symbolism, its emphasis on Celtic deities and folklore, and its adoption of the Celtic ritual festival calendar. Gerald Gardner, the founder of the original Wiccan faith, was a member of the Ancient Order of Druids and the Order of Bards, Ovates, and Druids. Gardner obviously had several influences, including writings on European fertility cults, Freemasonry, folklore, and the nineteenth century revival of medieval and Renaissance ritual magic. He incorporated elements of all of these into a new religion he called Wicca (according to Gardner, from a root meaning “wise”) and referred to it as a genuine ancient pagan tradition. Many of Gardner's occult flourishes proved unpopular over time, especially the elements of ritual magic, which were rightly perceived to have nothing to do with historical paganism. The Celtic elements, however, have resonated, so much so that many Wiccan splinter groups have embraced far more Celtic symbolism and cosmology into their practice.

Wiccan cosmology in general posits that there are two polar, harmoniously interacting energies in the universe, usually referred to as the god and goddess, who are sometimes said to represent all of the male and female deities of the world, night and day, and the interacting seasons of winter and summer.

In practice, Wiccans are free to choose among the deities they feel personally attracted to. Celtic deities are overwhelmingly popular for this purpose, and they probably make up the majority of deities venerated by Wiccan believers. The central mythology of Wicca is that of a horned god who takes the goddess as bride and continually dies and is reborn — a recasting of Cernunnos as a solar dying god. The goddess is less specific in attribute — not always recognizably Celtic, but nearly always linked with the Celtic horned god. In Wiccan mythology, the two deities represent the seasonal cycles, a continuing cycle of renewal.

The ritual and initiatory structure of Wicca and many of its offshoots in neopaganism are based on ritual magic, but strangely, its holidays and its emphasis on nature are mostly Celtic. The eight “Sabbats” of Wicca are, in fact, the eight festivals of the Celts: