Torvastad is a former municipality in Rogaland county, Norway. The municipality existed from 1838 until 1965. The administrative centre was the village of Haugesund (from 1838 until 1855), and after that it was the village of Torvastad on the island of Karmøy. Today, the area of Torvastad refers to the northern part of the municipality (and island) of Karmøy.
Torvastad municipality originally encompassed parts of the present-day municipalities of Haugesund, Utsira, and Karmøy. The municipality included the northwesternmost part of the mainland of Rogaland county plus the northern part of the island of Karmøy and the islands of Utsira, Røvær, Vibrandsøy, and Feøy. Upon its dissolution in 1965, the municipality was .
The parish of Torvestad was established as a municipality on 1 January 1838 (see formannskapsdistrikt law). On 1 February 1855 the village of Haugesund was declared a "ladested" (port of lading) and it was separated from Torvastad to form a municipality of its own. The split left Torvastad with 3,242 inhabitants. On 1 November 1881, most of the mainland part of Torvastad was separated to form the new municipality of Skaare. This left Torvastad with 1,918 residents. The island of Utsira was separated from Torvastad on 1 July 1924 to form the new municipality of Utsira. After the split, Torvastad was left with 2,187 residents.
On 1 January 1965, Torvastad municipality was dissolved upon recommendations of the Schei Committee. The small island of Vibrandsøy (population: 70) was transferred to the municipality of Haugesund. The rest of Torvastad, with 3,783 inhabitants, was merged with the neighboring municipalities of Avaldsnes, Kopervik, Skudenes, Skudeneshavn, Stangaland, and Åkra to form the new, much larger municipality of Karmøy.
The municipality (originally the parish) is named after the old Torvastad farm (Torfastaðir) since the first Torvastad Church was built there. The first element is the genitive case of the male name Torfi. The last element is the plural form of staður which means "farm" or "location".