Fabrici was born in Acquapendente and studied at Padua under Gabriele Falloppio, whom he succeeded as professor of anatomy. One of his pupils during his tenure was William Harvey.
By dissection of animals, Fabricius investigated the formation of the foetus, the structure of the oesophagus, stomach and bowels, and the peculiarities of the eye, the ear and the larynx. His main claim to fame is the discovery of the membranous folds, which he names valves, in the interior of veins.