'Bromley' probably means a bramble field – or a wood where broom grew.
The name first appears around the year 1000 as Braembeleg, one of the manors of St Paul's Cathedral. The station opened as Bromley in 1858 and in 1967 took the name Bromley-by-Bow, found already in Oliver Cromwell's letters, to avoid confusion with Bromley elsewhere in London. Bow comes from Stratford-at-Bow, after a medieval bridge built in the arched shape of a bow.