Fabrizio Mordente was born in 1532 in Salerno, a town in Campania (south-western Italy).
Until 1552 he studied philosophy and mathematics at the University of Naples. In the same year he left Naples and moved on to Crete, Cyprus, Palestine and Egypt, where he visited the pyramids and many places of Christian worship. From here he went to Mesopotamia, in search of the mythical Tower of Babel ruins, and reached the Persian Gulf, where he embarked on a Portuguese ship to India.
After a 3-years stay in the Portuguese colony of Goa, he took a ship to Lisbon rounding the Cape of Good Hope and through the Azores. After Portugal he went to Ireland to visit the legendary Well of St. Patrick, and then went to London, Paris and major cities in Europe before returning to Naples through Venice, Florence and Rome.
After returning to Europe, Mordente continued his peripatetic life, always in search of a post as mathematician in some European court.
The history of his scientific career began in Venice in 1567, where he published a treatise for his new compass (see the compass of Fabrizio Mordente).
Between 1568 and 1570 Mordente was in Urbino at the court of Duke Della Rovere, where he developed a new version of his compass and was probably involved in the field of fortifications.
In July, 1570 Mordente was hired by the Republic of Lucca for a consultation on the city walls. In 1572 he arrived at the Imperial Court to Vienna, where he presented to Emperor Maximilian II the third version of his compass (now kept at the Adler Planetarium in Chicago).
For the coronation of the new Emperor Rudolf II in 1576 Mordente prepared new instruments: one for dividing the circumference of a circle, a precision scale, and a new version of his compass. Mordente remained in Prague at the court of Emperor until 1585.
In 1585 Mordente travelled to Paris to the court of King of France, trying to obtain financing from the Queen Mother, Catherine de’ Medici, for a voyage. In Paris started the famous quarrel between Mordente and Giordano Bruno. Bruno was fascinated by the invention of Mordente and composed two dialogues (Mordentius and De Mordentii circino), with the approval of Mordente himself, to reveal the mathematical secrets of the compass. However, Bruno stated that Mordente was the unwitting bearer of a divine truth, that only men endowed with superior intelligence were able to interpret. Bruno’s dialogues attracted the attention of the scientific world, but cast a shadow over Mordente, who was suspected of plagiarism. Mordente naturally was furious (he had a reputation as a difficult and irascible man) and accused Bruno of arrogance, the latter replied with two more dialogues, in which "the god of geometers", as he had called Mordente in his previous dialogues, suddenly became "the triumphant idiot".
The offended Mordente not only buyed and destroyed the printouts of dialogues of Bruno, but also used his good relationship with Henry I, Duke of Guise to turn the Catholic world against Bruno, who was forced to flee Paris.
In 1587 Mordente entered the service of Henry I, Duke of Guise, in Antwerp. In Antwerp he designed war machines and wrote the treatise Offensive and Defensive Machines
In 1591 Mordente was hired at the court of Alessandro Farnese, Duke of Parma and Piacenza and Governor of the Spanish Netherlands. At that time Mordente wrote a treatise, in which he announced the birth of a new science, the so called "science of residues", intended as a response to Bruno’s accusations.
After the death of his patron Alessandro Farnese in December, 1592, Mordente remained for some time in Flanders, but later decided to return to Italy. In January 1596 he settled down in Rome, where he lived up to his death in 1608.
Fabrizio Mordente had a younger brother—Gasparo, who was is the inventor of the parallel ruler (instrument formed of two rulers attached to two arms along which they slide parallel to each other).