The administrative centre of the municipality was located in the adjacent villages of Nevlunghavn and Helgeroa. Arguably the best soil in Vestfold County can be found in Brunlanes, and farming is the main industry with considerable vegetable- and corn cultivation. It is home to Berg Old Church at Berg, which was erected in the 1100s, but laid in ruins by the 1960s. The church had been rebuilt and features a clear-cut architecture with a red tilestone roof.
The parish of Brunlagnæs was established as a municipality January 1, 1838 (see formannskapsdistrikt). Small parts of Brunlanes were moved to Larvik in 1875 and to the neighboring municipality Stavern in 1883, 1938, 1949 and 1969. In 1964 three farms with 12 inhabitants were moved to Porsgrunn in Telemark county. On 1 January 1988 Brunlanes was incorporated into the enlarged Larvik municipality. Before the merger it had a population of 8,138. today Brunlanes constituting the south-western part of Larvik. Villages including Helgeroa and Nevlunghavn are located there. Its area is 188 km². 
There are large areas of good agricultural within Brunlanes. The area is known for strawberry cultivation. Brunlanes is also known for forestry and wood processing industry. There are many historical relics in Brunlanes, including many burial mounds from the Iron Age and Bronze Age. The large moraine runs into the ocean at far southwestern Brunlanes.
Until 1879 the name was written "Brunlagnæs" (with variations), and in the period 1879-1888 "Brunlanæs". The form "Brunlanes" was settled in 1889. The Old Norse form of the name was just Nesjar, the plural form of nes n 'headland'. But the parish (and the municipality) was later named after the old farm Brunla. The first element in this name is probably brunnr m 'well', or brún f 'edge; steep slope'. The last element is lá f 'meadow near the water'.
Brunlanes Parish in Larvik (Brunlanes prestegjeld) includes Tanum Church (Tanum kirke) in Brunlanes, Kjose church (Kjose kirke) at Farris, Berg wood church (Berg trekirke) and Berg stone church (Berg steinkirke).    
Berg stone church (Berg steinkirke) was built of brick in ca. 1100. The old medieval church was partially demolished in 1882, after Berg trekirke had been built on the site in 1878. The remains of the walls were preserved and from 1965 to 1970, the church was restored partly with the original stone. The church has conservation status protected.