Francesco Foscari was born in 1373, as the oldest son of Nicolò Foscari and his wife Cateruzia Michiel. The Foscari family had been of only moderate importance, but had managed to become one of the few noble families that secured a hereditary place in the Great Council of Venice after the so-called "Serrata" ("Closing") of the Great Council, and had begun to rise in prominence throughout the 14th century. Francesco's ancestors began holding high public office, and his father Nicolò even became a member of the powerful Council of Ten.