According to Pindar's ninth Pythian Ode, Cyrene rejected the traditional pursuits of women, preferring hunting and shepherding. Apollo carried her off to Libya, where he founded the city of Cyrene. When Aristaeus was born, Hermes took him to be raised on nectar and ambrosia, conferring immortality upon him. Pindar notes that 'Aristaios' served as an epithet rather than a name, numbered among the titles different peoples applied to Zeus and Apollo.

Diodorus Siculus recounts that Aristaeus was born in Libya and reared by nymphs who taught him dairying, beekeeping, and the cultivation of the olive. He later moved to Boeotia, married Autonoe, daughter of Cadmus, and fathered Actaeon. After Actaeon's death an oracle directed him to Ceos, where his sacrifices ended a plague. He then traveled to Sardinia, Sicily, and Thrace, where Dionysus initiated him into secret rites. He finally settled on Mount Haemus in northern Thrace, ceased to appear among mortals, and was venerated as a god.

In Virgil's Georgics, Aristaeus inadvertently caused the death of Eurydice, the wife of Orpheus. As punishment his bees sickened and began to die. Consulting his mother Cyrene and the sea-god Proteus, he learned the cause of the affliction. To make amends he sacrificed cattle and left their carcasses at an altar; returning three days later he found new swarms of bees generated within the carcasses, which he carried to his apiary, ending the disease. This is the legendary origin of bugonia, the supposed spontaneous generation of bees from oxen.

Aristaeus was the patron god of a great range of rustic arts, each learned from a divine teacher. From Chiron, the Muses, and Apollo he gained prophecy, healing, and herblore, presiding over physic gardens; from Artemis and his mother Cyrene he learned hunting, the dressing of meat and skins, and the use of nets.

From the Thessalian nymphs he received the secrets of the dairy — making cream, butter, oxygala, and cheese from milk — and of beekeeping, taming bees and keeping them in hives. He was protector of olive trees and orchards, of oliviculture and the olive press, and patron of herding, sheep-shearing, pastoralism, cattle, and pastures.

Other gods extended his domain still further: Dionysus taught him wine and mead and made him protector of grapevines, vineyards, and winepresses; Demeter gave him agriculture and the guardianship of gardens, farms, fields, and orchards; Hestia gave him cooking and baking and the quern-stones, mills, and ovens; Poseidon gave him fishing; Athena gave him weaving, ropemaking, net-making, and basket-weaving; and Hephaestus gave him the crafts of the clay kiln, masonry oven, and charcoal pile.

Aristaeus married Autonoe, daughter of Cadmus, founder of Thebes. By her he was the father of Actaeon, the hunter who was devoured by his own hounds, and of Macris, who is said to have nursed the infant Dionysus.

In Sardinia he was credited with two further sons, Charmus and Callicarpus. According to Pherecydes he was also the father of Hecate, goddess of witchcraft and crossroads, although Hesiod's Theogony instead names her parents as Perses and Asteria.

Attestations of Aristaeus' presence on the island of Ceos date to the fourth and third centuries BC. A Delphic oracle directed him to sail there, promising him great honor. On arrival he found the islanders suffering sickness brought by the rising of the Dog-Star Sirius in early July.

He performed a double sacrifice to counter the star's deadly heat: a pre-dawn chthonic sacrifice to Sirius itself, followed at dawn by a sacrifice to Zeus Ikmaios, 'Rain-making Zeus,' at a mountaintop altar. The ritual summoned the cooling Etesian winds, which brought forty days of relief across the Aegean. An alternative account holds that Aristaeus exposed the murderers of Icarius who were hiding among the Ceans, and that after their execution and the building of a shrine to Zeus Ikmaios the god decreed the Etesian wind should blow; the Ceans thereafter continued to propitiate Sirius before its rising.

Aristaeus appears on Cean coins. He was also said to have visited Arcadia, where a winged male figure depicted on ivory tablets in the sanctuary of Ortheia was identified with him, and to have settled for a time in the Vale of Tempe.

The word 'Aristaios,' meaning 'the best,' functioned originally as a cult title rather than a personal name, applied to the pastoral god across Boeotia, Arcadia, Ceos, Sicily, Sardinia, Thessaly, and Macedonia. He held greater prominence in Boeotia than at Athens, where he was known as 'the pastoral Apollo.'

In later times Aristaios became a familiar Greek personal name in its own right, borne by several archons of Athens and attested in inscriptions.