It is bordered by the Shan State of Myanmar to the north, Bokeo province of Laos to the east, Phayao to the south, Lampang to the southwest, and Chiang Mai to the west.

The north of the province is part of the so-called Golden Triangle, where the borders of Thailand, Laos and Burma converge, an area which prior to the rise of agricultural production of coffee, pineapple, coconuts, and banana plantations, was unsafe because of drug smuggling across the borders.

While not the highest elevation of the province, the 1,389-metre (4,557 ft) high[5] Doi Tung (Flag Hill) is the most important terrain feature.

Chiang Rai province's golden triangle bordering Laos and Burma was once the hub of opium production.

[9] The majority of the population are ethnic Thai who speak Kham Muang among themselves, but 12.5% are of hill tribes origin, a sizeable minority in the north provinces.

A smaller number are of Chinese descent, mainly descendants of the Kuomintang soldiers who settled in the region, notably in Santikhiri.

Khon Muang are the city folk who originally came from Chiang Mai, Lamphun, Lampang, and Phrae.

Chin Haw in Chiang Rai consist primarily of the former Kuomintang (KMT army) who took refuge in the area, mainly in Santikhiri (formerly Mae Salong).

Tai Lue (Dai) live in dwellings of usually only a single room wooden house built on high poles.

Lisu from southern China and Tibet are renowned for their colorful dress and also build their dwellings on high stilts.

The current slogan is "เหนือสุดในสยาม ชายแดนสามแผ่นดิน ถิ่นวัฒนธรรมล้านนา ล้ำค่าพระธาตุดอยตุง", 'Northernmost of Siam, frontier of three lands, the home of Lan Na culture and Doi Tung Temple'.

[11] Another attraction is the Golden Triangle, which is the meeting point of Thailand, Laos, and Myanmar and offers views of the Mekong River and the surrounding mountains.

As of 26 November 2019 there are:[13] one Chiang Rai Provincial Administration Organisation (ongkan borihan suan changwat) and 73 municipal (thesaban) areas in the province.

The non-municipal areas are administered by 70 Subdistrict Administrative Organisations - SAO (ongkan borihan suan tambon).