Regency architecture encompasses classical buildings built in the United Kingdom during the Regency era in the early 19th century when George IV was Prince Regent, and also to earlier and later buildings following the same style. The period coincides with the Biedermeier style in the German-speaking lands, Federal style in the United States and the French Empire style. Regency style is also applied to interior design and decorative arts of the period, typified by elegant furniture and vertically striped wallpaper, and to styles of clothing; for men, as typified by the dandy Beau Brummell and for women the Empire silhouette.

The style is strictly the late phase of Georgian architecture, and follows closely on from the neo-classical style of the preceding years, which continued to be produced throughout the period. The Georgian period takes its name from the four Kings George of the period 1714–1830, including King George IV. The British Regency strictly lasted only from 1811 to 1820, but the term is applied to architecture more widely, both before 1811 and after 1820; the next reign, of William IV from 1830 to 1837, has not been given its own stylistic descriptor. Regency architecture is especially distinctive in its houses, and also marked by an increase in the use of a range of eclectic Revival styles, from Gothic through Greek to Indian, as alternatives to the main neoclassical stream.

The opening years of the style were marked by greatly reduced levels of building because of the Napoleonic Wars, which saw government spending on building eliminated, shortages of imported timber, and high taxes on other building materials. In 1810 there was a serious financial crisis, though the only major asset class not to lose value was houses, at least in London, mainly because the low level of recent building had created pent-up demand. After the decisive victory at the Battle of Waterloo in 1815 ended the wars for good, there was a long financial boom amid greatly increased British self-confidence. Most Regency architecture comes from this period.