It is located about 20 km north of Stockholm, with a part situated by the shore of Lake Mälaren.

Furthermore, the centre of the hundred was located within the boundaries of the municipality from 1675 to 1905 Its coat of arms, which depicts a golden lamb carrying an archbishop's cross, can be traced from 1568, but was created in 1955.

They may symbolize that Järfälla is situated on the road from the capital Stockholm to the seat of the archbishop in the nearby city of Uppsala.

The main population expansion came in the 1930s and 1940s, when many residential houses were built in the seat Jakobsberg for middle-class families commuting to Stockholm.

There are three Stockholm commuter rail stations, Barkarby, Jakobsberg and Kallhäll, as well as a bus network.