The Romans are thought to have built a camp at Keston,where a natural spring known as Caesar's Well is the source of the Ravensbourne. Some time after the Roman era, an Anglo-Saxon settlement developed around the location now occupied by the market square - the name Bromley (first recorded in 862 as Bromleag) means Anglo-Saxon 'the place where broom grows'.

In the 10th century, Bromley was chosen by the Bishops of Rochester to be their base for visitors to London; the latest Bishop's Palace, built in 1775, with its moat, now forms part of the extensive Bromley Civic Centre. The last bishop to be based in Bromley moved away in 1845. The granting of a royal charter to the town's market by King John in 1205 gave a major boost to Bromley's development and prosperity.

The growth of the railway system turned the northern half of the borough into a dormitory for London, although most of the southern half remains open countryside. Subsequently, the town has grown to become one of the most important commercial and shopping centres in South East England.

Several literary giants lived in Bromley including H.G. Wells and Richmal Crompton, author of the "Just William" books.

One of the saddest events in the history of this part of London was the destruction by fire in 1936 of the Crystal Palace, a huge steel-and-glass exhibition hall set in a park at Penge. The building had been relocated here in 1854 from its original site in Hyde Park for the Great Exhibition in 1851.

During the Second World War, Biggin Hill Aerodrome, at the south end of the borough, achieved immortality as a base for RAF Fighter Command. It has since become a civil airport, extensively used by private aircraft and for flying displays, as well as a major source of employment.