Neo-Byzantine architecture is a somewhat uncommon architectural revival style, of the mid- to late 19th and early 20th centuries, most frequently seen in religious, institutional and public buildings. Neo-Byzantine architecture incorporates elements of the Byzantine style associated with Eastern and Orthodox Christian architecture dating from the 5th through 11th centuries, notably that of Byzantium (Constantinople, or modern-day Istanbul).

The style is characterized by round arches, vaults and domes, brick and stucco surfaces, symbolic ornamentation, and the use of decorative mosaics.

The Neo-Byzantine style was popular in 19th century Russia and Eastern Europe and was used to great effect by the Russian architect Konstantin Ton, who often combined it with Neo-Muscovite stylistic elements.

Notable American examples include many buildings on the campus of Rice University in Texas, and the Basilica of the National Shrine of the Immaculate Conception built between 1920 and 1959 in Washington, D.C. In the early 1980s, famed American architect Philip Johnson designed a Post-Modernist addition to the Cleveland Play House that reflects Byzantine influences, and could thus be termed Neo-Byzantine.

In the United States and elsewhere, the Neo-Byzantine style is often seen in vernacular amalgamations with other Medieval revivalist styles such as Romanesque and Gothic, or even with the Mission or Spanish Colonial styles.