Phuket's Vegetarian festival (or jia chai in local Hokkien Chinese dialect) began in 1825, when the govenor of Thalang, Praya Jerm, moved the island's principal town from Ta Reua in Thalang District to Get-Hoe in Kathu District, where were tin mines and Chinese miners. Kathu was then still covered by jungle and fever was rife. It happened that a traveling opera company (called ngiu in Thai or pua-hee in Hokkien dialect) came from China to perform for the miners

When the whole company grew sick from an unnamed malady, they kept to a vegetarian diet to honor two of the emperor gods, Kiew Ong Tai Teh and Yok Ong Sone Teh. The sickness afflicting the opera troupe then disappeared. This greatly interested the people of Kathu, who asked how it was done. The answer came that ritual vegetarianism with its attendant ceremonies had been the cause, with the result that people embraced the faith enthusiastically. Thus the festival began:starting the first evening of the ninth lunar month, it continued until the ninth evening; the aim was to bring good luck to individuals as well as to the community.

It later happened that one familiar with the festival volunteered to return to Kansai, in China, where he invited the sacred Hiao Ho-le or Hiao lan (incense smoke) and Lian Tui (name plaques), which have the status of gods, to come stay in Kathu. He also brought holy writings used in the ceremonies, returning to Phuket on the seventh night of the ninth month. The people, upon hearing of his arrival, went in procession to Bang Niao Pier to bring him and his sacred cargo back. This was the origin of the processions that figure so greatly in the festival.

The afternoon before the festival begins, a great pole at each temple is raised, called the Go Teng pole, with which the gods are invited to descend. At midnight the pole is hung with nine lanterns, signalizing the opening of the fest. Two important gods are also invited down at midnight to preside over ceremonies; these are Yok Ong Hong Tae and Kiew Ong Tai Tae.

Aside from this, there are other ceremonies throughout the fest, notably: invocation of the gods Lam Tao, who keeps track of the living, and Pak Tao, who keeps track of the dead; processions of the gods' images; and feats of the Ma Song-like bathing in hot oil, bladed ladder climbing and fire-walking. The festival ends with merit making ceremonies at each temple (sadoh kroh) and the send-off of the gods on the last night (when fireworks are at their most impressive).

Ma Song, or entranced horses, are devotees whom the gods enter during the fest. They manifest supernatural powers and perform self-tortures in order to shift evil from individuals onto themselves, and to bring the community good luck. Ma Song fall into two categories: those who, having had an intimation of impending doom, want to extend their lives; and people specially chosen by the gods for their moral qualities.

Throughout the festival fireworks and drums are sounded, especially during ceremonies. It is held that the louder they are the better, because the noise drives away evil spirits.

Participants in the fest keep to a strict vegetarian diet for a varying number of days, usually no less than three. This they do to make themselves strong in mind and body; they refrain from all vice, eating animal flesh, and killing animals. The festival thus promotes good hygiene, brightness and inner peace.