The siege of Constantinople in 1394–1402 was a long blockade of the capital of the Byzantine Empire by the Ottoman Sultan Bayezid I.

After constructing the fortress of Anadoluhisarı to control the Bosporus strait, Bayezid tried to starve the city into submission by blockading it both by land and, less effectively, by sea.

In 1399, a French expeditionary force under Marshal de Boucicaut arrived, but was unable to achieve much.

The situation became so dire that in December 1399 the Byzantine emperor, Manuel II Palaiologos, left the city to tour the courts of Western Europe in a desperate attempt to secure military aid.

Bayezid's defeat in the Battle of Ankara in 1402 and the subsequent Ottoman civil war enabled the Byzantines to regain some lost territories in the Treaty of Gallipoli.