Sandefjord (Norwegian pronunciation: [ˈsɑ̂nːəfjuːr] ) is a municipality in Vestfold county, Norway. It is located in the traditional district of Vestfold. The administrative centre of the municipality is the city of Sandefjord. Other population centres in Sandefjord include Andebu, Fevang, Fokserød, Fossnes, Freberg, Hafallen, Helgerød, Himberg, Høyjord, Kodal, Lahelle, Melsomvik, Råstad, Solløkka, Stokke, Storevar, Strand, and Unneberg.
The 422-square-kilometre (163 sq mi) municipality is the 233rd largest by area out of the 356 municipalities in Norway. Sandefjord is the most populous municipality in Vestfold and the 14th most populous municipality in Norway, with a population of 67,009 (2025). The municipality's population density is 158.7 inhabitants per square kilometre (411/sq mi) and its population has increased by 6.6% over the previous 10-year period.