The city was founded by King Mangrai in 1262 and became the capital of the Mangrai dynasty. Subsequently, Chiang Rai was conquered by Burma and remained under Burmese rule for several hundred years. It was not until 1786 that Chiang Rai became a Chiang Mai vassal. Siam (Thailand) annexed Chiang Mai in 1899, and Chiang Rai was proclaimed a province of Thailand in 1933.

In 1432, during the reign of King Sam Fang Kaen of Mangrai dynasty (1402–1441), the Phra Kaeo, or Emerald Buddha, the most revered Buddha statue, was discovered in Chiang Rai when an earthquake split the Chedi at Wat Phra Kaeo of Chiang Rai City. The beautiful jade figure was then seen concealed within. Another telling of the story has the 'Emerald Buddha' hastily covered in mud just before marauders entered to pillage. Many years later, the clunky-looking mud Buddha was found to actually house the magnificent jade statue, perhaps by way of the earthquake mentioned above - which caused a piece of the clay to break off - revealing the jade beneath.

In 1992, the City Pillar was moved from Wat Klang Wiang to Wat Phra That Doi Chom Thong, where it is known as Sadue Mueang (Thai: สะดือเมือง), the Navel or Omphalos of the City.