Westminster Bridge was built between 1739–1750 under the supervision of Swiss engineer Charles Labelye.

For over 600 years, the nearest Thames bridge to London Bridge had been at Kingston. A bridge at Westminster was proposed in 1664, but opposed by both the Corporation of London and watermen. A bridge was built at Putney in 1729 and the Westminster Bridge scheme finally received parliamentary approval in 1736. Financed by private capital, lotteries and grants, Westminster Bridge opened on 18 November 1750.

The bridge assisted the development of south London. Roads on both sides of the river were built and improved, including Charing Cross Road and the area around the Elephant & Castle.

By the mid-19th century the bridge was subsiding badly and expensive to maintain. The current bridge was designed by Thomas Page and opened on 24 May 1862. Since the removal of Rennie’s New London Bridge in 1967 it is the oldest road structure which crosses the Thames in central London.

Westminster Bridge is painted predominantly green, the same colour as the leather seats in the House of Commons which is on the side of the Palace of Westminster nearest to the bridge. This is in contrast to Lambeth Bridge, which is red, the same colour as the seats in the House of Lords and is on the opposite side of the Houses of Parliament.