Thanh Hóa is the northernmost coastal province in the North Central Coast region of Central Vietnam. It borders Sơn La, Hòa Bình, and Ninh Bình to the north, Nghệ An to the south, the Laotian province of Houaphanh to the west with a boundary of over 192 kilometres (119 mi) long, and the South China Sea (Gulf of Tonkin) to the east.

Thanh Hóa is a relatively large province; it ranks fifth in area and third in population among 63 central administrative subdivisions. Its capital and largest city is Thanh Hóa City. The province has a nickname: Xứ Thanh (The Land of Thanh).

Human civilization has existed in Thanh Hóa since about 6,000 years ago and was one of the earliest centers of the ancient Vietnamese. Archaeological excavations have shown that the first culture present was the Đa Bút Culture, located along the Đáy and the Mã Rivers.

Thanh Hóa is located in the middle of North Vietnam and the North Central Coast as a transition in many aspects: geology, climate, administrative division, and local culture. These factors show that it has many particular local habits, customs, and cultures.

Thanh Hóa has two provincial cities, one district-level town and 24 rural districts with an area of 11,114.71 km (4,291.41 sq mi), and a population of approximately 3.6 million. Sầm Sơn city is a famous seaside resort situated 16 km from the Thanh Hóa city centre. Bỉm Sơn township is a large industrial centre, especially for cement. Nghi Sơn is a promising economic zone, expected to become the centre of Thanh Hoa's industry with a large refinery factory, deepwater seaport, and many projects in progress.

The province is also home to many ethnic groups, the seven ethnicities with most people are Kinh, Mường, Thái, H'Mông, Dao, Thổ, Khơ-mú with mentions of the legend Long Quân. ("Dragon Lord of Lac")

The coordinate was accurately measured as 19°18'N - 20°40'N (from the southernmost point to northernmost point), 104°22'E - 106°05'E (from the westernmost point to easternmost point).

Thanh Hóa is subdivided into 27 district-level sub-divisions:

• 23 rural districts:

• 2 district-level towns:

• 2 provincial cities:
  • Thanh Hóa (capital)
  • Sầm Sơn

They are further subdivided into 28 commune-level towns (or townlets), 579 communes, and 30 wards.

Thanh Hóa province is the hometown of many emperors in history, so Valedictorian-Fine Artist Vũ Tú personally gave this province the title "King" Region of Vietnam (Vietnamese: Miền quân vương nước Việt).

The province's name derives from Sino-Vietnamese 清化.

清 "Thanh" meaning clear; pure; fine. 化 "Hóa" meaning “to transform; to change into; to become”.

• Official Site of Thanh Hóa Government
• Official Site of Thanh Hóa City Government