As in Hinduism, the Buddhist nāga generally has the form of a great cobra, usually with a single head but sometimes with many. At least some of the nāgas are capable of using magic powers to transform themselves into a human semblance. The nāga is sometimes portrayed as a human being with a snake or dragon extending over his head. One nāga, in human form, attempted to become a monk; and when telling it that such ordination was impossible, the Buddha told it how to ensure that it would be reborn a human, and so able to become a monk.

The nāgas are believed to both live on Nagaloka, among the other minor deities, and in various parts of the human-inhabited earth. Some of them are water-dwellers, living in streams or the ocean; others are earth-dwellers, living in caverns.

The nāgas are the followers of Virūpākṣa (Pāli: Virūpakkha), one of the Four Heavenly Kings who guards the western direction. They act as a guard upon Mount Sumeru, protecting the dēvas of Trāyastriṃśa from attack by the asuras.

Among the notable nāgas of Buddhist tradition is Mucalinda, Nāgarāja and protector of the Buddha. In the Vinaya Sutra (I, 3), shortly after his enlightenment, the Buddha is meditating in a forest when a great storm arises, but graciously, King Mucalinda gives shelter to the Buddha from the storm by covering the Buddha’s head with his seven snake heads. Then the king takes the form of a young Brahmin and renders the Buddha homage.

In the Vajrayāna and Mahāsiddha traditions, nāgas in their half-human form are depicted holding a nāgas-jewel, kumbhas of amrita, or a terma that had been elementally encoded by adepts.

The two chief disciples of the Buddha, Sariputta and Moggallāna are both referred to as Mahānāga or “Great nāga”. Some of the most important figures in Buddhist history symbolize nāgas in their names such as Dignāga, Nāgāsēna, and, although other etymons are assigned to his name, Nāgārjuna.