San Biagio is a church dedicated to Saint Blaise, in the sestiere of Castello in Venice, northern Italy.

The church now stands adjacent to the Museo Storico Navale, and is officiated by a military chaplain.

Till 1511, this served as the church for the Greek community which had emigrated to Venice after the Fall of Constantinople.

On the left hand wall is a funerary monument with the heart of Archduke Friedrich of Austria (1821–1847).

The tomb of Admiral Angelo Emo (died 1792) has a statue (1818) by Giovanni Ferrari.