The pilgrim road to Trondheim that was established after 1030 went through Bærum, and there is evidence that lime kilns were in use in the area in 850. There were shipping ports for the quicklime at Slependen and Sandvika. The lime kiln is the main motif for the municipality's coat of arms.
In the 1600s, iron ore was discovered in Bærum and the iron works at Bærums Verk were founded. Industries such as paper mills, nail factories, sawmills, glassworks, and brick works were established along the rivers Lysakerelven and Sandvikselven in the following centuries. There were orchards and other agricultural concerns throughout the area, remnants of which still exist today.
A number of artists established themselves in Bærum, particularly around the art school run by Johan Fredrik Eckersberg. Among the artists who did much of their work in Bærum are Fritz Thaulow, Christian Skredsvig, Harriet Backer, Kitty Kielland, Otto Sinding, Eilif Pettersen, Gerhardt Munthe, and Erik Werenskiold.
Starting in the mid-20th century, Bærum's agricultural base gradually gave way to residential construction. Still, only a third of the area (64 km²) is built up for residential use; over half is productive forestry, and nearly 17 km² is still agricultural.
The name (Norse Bergheimr) is composed of berg n "mountain" and heimr m "homestead, farm". It has probably originally belonged to a farm lying beneath the prominent mountain Kolsås. In Norse times the municipality was often called Bergheimsherað 'the herað ("parish, district") of Bergheimr.'
The geology of Bærum also offers some of the best examples of the distinct diversity of the Oslo region's rocks, formations, and fossil finds.
Bærum's forested surroundings offer great opportunities for outdoor activities, such as skiing, hiking and fishing. Inhabitants are generally eager to use "Marka" - a popular name for the forest belt which starts at Vestmarka, continues through Kroksskogen, Bærumsmarka, Nordmarka and Lillomarka and ends up at Østmarka. Lillomarka, Østmarka and parts of Nordmarka belongs to Oslo. Marka is an area where cars and motorized vehicles are not allowed. The gravel roads through Marka is closed with gates, but there are large car parking areas outside the gates. These car parks are often very full during the weekends.
Administratively, Bærum is divided into 22 sections. The population in each section per January 1, 2005:
Two of Norway's busiest highways (E18 and E16) and one railroad traverse the municipality. There has been considerable development of office parks along E18, especially around Lysaker in the last 20-30 years, reducing some of the pressure on downtown areas of Oslo.
Bærum is also the most affluent of Norwegian municipalities, with average per capita income (2002 figures) of NOK 370,800, compared with the national average of NOK 262,800, and also has the highest level of education nation-wide.