Notodden (pronunciation^ⓘ) is a municipality in Telemark county, Norway. It is located in the traditional district of Aust-Telemark. The administrative centre of the municipality is the town of Notodden. Other population centres include the villages of Bolkesjø, Gransherad, Heddal, Hjuksebø, Hjuksevelta, Rudsgrendi, Tinnoset, and Yli.

The 984-square-kilometre (380 sq mi) municipality is the 118th largest by area out of the 356 municipalities in Norway. Notodden is the 94th most populous municipality in Norway with a population of 13,025. The municipality's population density is 14.3 inhabitants per square kilometre (37/sq mi) and its population has increased by 4.2% over the previous 10-year period.

Norway's largest stave church, Heddal Stave Church, is located in Heddal, a few kilometres west the municipal centre. Notodden Airport, is located west of the town of Notodden, along the European route E134 highway. Norsk Hydro was founded in this town. Notodden is well known for the annual Notodden Blues Festival, which is considered one of the best blues festivals in Europe. It also has a well-known metal festival called Motstøy Festivalen. The football club Notodden FK is headquartered here.

On 1 January 1913, the newly-designated kjøpstad (town) of Notodden (population: 4,821) was separated from Heddal Municipality to form a separate self-governing town as an enclave within Heddal Municipality. This left Heddal with 2,890 residents. During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1964, Heddal Municipality was dissolved and the following areas were merged to form a new, larger Notodden Municipality:

The municipality (originally the town) is named after a small cotter's farmstead (husmannsplass) located on the old Tinne farm since this was the original site of the town (near the mouth of the river Tinnelva at the lake Heddalsvatnet). The first element is derived from the word nót which means "to fish using a seine". The last element is the definite singular form of odde which means "headland". Thus it is a "headland for net fishing".

The coat of arms was granted on 11 August 1939. The official blazon is "Azure, a pale wavy and four lightning bolts in saltire argent" (Norwegian: På blå bunn en loddrett sølvelv som sender lynstråler av sølv til begge sider). This means the arms have a blue field (background) and the charge is a wavy vertical bar and four lightning bolts emanating from the centre and making an X-shape. The charge has a tincture of argent which means it is commonly colored white, but if it is made out of metal, then silver is used. The design symbolizes that Notodden was created by the exploitation of hydroelectric power on the river Tinnelva when Norsk Hydro started its operations with saltpeter production and power development in 1905. The vertical bar represents the Tinnfoss waterfall along the river and the lightning bolts represent electricity. The arms were designed by Jens Høibø. The municipal flag has the same design as the coat of arms.

The Church of Norway has four parishes (sokn) within the municipality of Notodden. It is part of the Øvre Telemark prosti (deanery) in the Diocese of Agder og Telemark.

Notodden Municipality is responsible for primary education (through 10th grade), outpatient health services, senior citizen services, welfare and other social services, zoning, economic development, and municipal roads and utilities. The municipality is governed by a municipal council of directly elected representatives. The mayor is indirectly elected by a vote of the municipal council. The municipality is under the jurisdiction of the Telemark District Court and the Agder Court of Appeal.