Born in Venice, Cacciari graduated in philosophy from the University of Padua (1967), where he also received his doctorate, writing a thesis on Immanuel Kant’s Critique of Judgment.
In 1985, he became professor of Aesthetics at the Architecture Institute of Venice. In 2002, he founded the Department of Philosophy at the University of Vita-Salute San Raffaele in Milan, where he was appointed Dean of the Department in 2005.
Cacciari has founded several philosophical reviews and published essays centered on the «negative thought» inspired by authors like Friedrich Nietzsche, Martin Heidegger and Ludwig Wittgenstein.
After a brief affiliation with Potere Operaio, a radical left-wing worker’s party, Cacciari joined the Italian Communist Party (PCI). In the 1970s he was responsible for industrial politics for the PCI Veneto section and, in 1976, he was elected to the Italian Chamber of Deputies, where he was a member of the Parliamentary commission for industry (1976–1983).
After the death of Enrico Berlinguer (1984), Cacciari left the Communist Party and switched to more moderate positions, although he never left the centre-left coalition. In 1993 he was elected mayor of Venice, a position he held until 2000.
He was also put forth as the future national leader of the coalition, later named The Olive Tree, but his defeat in the 2000 election as governor of the Veneto region made this occasion wane. However, in a surprise move in 2005, Cacciari was elected againmayor of Venice.