Tromsø (Northern Sami: Romsa, Kven: Tromssa) is a municipality in Troms and Finnmark counties. Tromsø municipality is the most populous municipality in northern Norway and the ninth largest municipality in Norway.

In the municipal center, the city of Tromsø, is the seat of Troms and Finnmark counties, of the bishop of Nord-Hålogaland diocese, of the Arctic Council and the University of Tromsø. Tromsø belongs to Troms police district, Nord-Troms district court and Hålogaland court of appeal.

Tromsø municipality had 76,975 inhabitants as of 1.1.2020. The central urban area consists of several Statistics Norway-defined settlements. Tromsø settlement on Tromsøya had 40,926 inhabitants as of 1 January 2020, Tromsdalen 17,495 inhabitants, Kvaløysletta 8,951 inhabitants. In addition, the smaller settlements Kjosen (377), Fagernes (287) and Movik (356) are also included in the urban area, which as of 1 January 2017 had 65,461 inhabitants.

The city's largest workplaces are UiT Norway's Arctic University (UiT) and the University Hospital of Northern Norway. The front center was established on 29 September 2010 and houses, among other things, the Norwegian Polar Institute, which is headquartered in Tromsø. The Northern Lights Observatory was established in 1928, and two companies affiliated with the Kongsberg Group that download satellite data from space on behalf of Norway and abroad. The fishing industry is of great importance. The Norwegian Raw Fish Association and the Norwegian Seafood Council are headquartered in Tromsø. SpareBank 1 Nord-Norge also has its headquarters in the city. Furthermore, Tax North and several smaller institutions are located in Tromsø.

Tromsø is a distinct service municipality with just over 3/4 of the municipality's employed employees in public and private services or business activities.

Tromsø municipality received its current extent on 1 January 2008 when the southern part of Reinøya was transferred to Karlsøy municipality. The biggest change took place on 1 January 1964 when the city municipality was merged with the neighboring municipalities Tromsøysund, the Kvaløy part of Hillesøy (Senja part to Lenvik) and most of Ullsfjord (Svensby area to Lyngen). The Tromsø region consists of the municipalities of Tromsø and Karlsøy, and since 2003 has been one of 16 urban regions in Norway. The Tromsø region has 75,762 inhabitants as of 1 January 2020. Since 2010, the municipalities of Tromsø, Karlsøy and Balsfjord are part of the Tromsø area's regional council.