Eco, who had been suffering from cancer, passed away at his home late on Friday, La Repubblica said on its website.
"The world has lost one of the most important men in contemporary culture," the daily said, while the Corriere della Sera said: "Umberto Eco, one of Italy's most celebrated intellectuals, is dead."
Eco was born on January 5, 1932, at Alessandria in the northern Italian region of Piedmont.
He leaves a wife, Renate Ramge Eco, a German art teacher whom he married in 1962 and with whom he had a son and a daughter.
His family name was reportedly an acronym of the Latin ex caelis oblatus, "a gift from the heavens", which was given to his grandfather, a founding father, by a city official.
The young Umberto had a Roman Catholic upbringing, being educated at one of the Salesian institution's schools.
His father was very keen for him to read law, but instead he took up medieval philosophy and literature at the University of Turin.
In the late 1950s, he started to develop ideas on semiotics -- the study of signs, communicated either as spoken, written, scientific or artistic language.
"Books are not meant to be believed, but to be subjected to inquiry. When we consider a book, we mustn't ask ourselves what it says, but what it means," Eco said on his website.
Eco was appointed professor of semiotics at Bologna University in the 1970s and published a treatise laying out his theories.
His breakthrough, to a far wider audience, came in 1980 with the success of novel "The Name of the Rose", which has since been translated into 43 languages and sold millions of copies.
- 'Change' the reader -
A gothic murder mystery set in an Italian medieval monastery, it combines semiotics, biblical analysis, medieval studies and literary theory.
It was adapted for the big screen by Jean-Jacques Annaud in 1986, starring Sean Connery as the detective monk William of Baskerville and Christian Slater as his young assistant, Adso of Melk.
Eco was also successful with "Foucault's Pendulum" (1988), about three employees at a minor publishing house who concoct a fictional conspiracy about a medieval Christian sect called the Knights Templar for fun.
Alarmingly, they find themselves enmeshed in a real-life drama, targeted by a secret society who believe they hold the key to the sect's lost treasure.
Eco, who continued his academic work late in life, wrote several other major novels including "The Island of the Day Before" (1994), "Baudolino" (2000) and "The Prague Cemetery" (2010), which describes staging posts in the rise of modern anti-Semitism.
Among his dozens of essays on semiotics, medieval aesthetics, linguistics and philosophy, two in particular gained enduring popularity with their analysis of cultural standards.
They are "History of Beauty" (2004), and "On Ugliness" (2007) -- explorations what we consider to be physically attractive or repellant, and why.
British daily The Guardian hailed Eco as "one of the world's most revered literary names".
In an interview with the paper last year, he said that his approach to writing was to seek to "change" the reader.
"I don't know what the reader expects," he said. "I think an author should write what the reader does not expect. The problem is not to ask what they need, but to change them... to produce the kind of reader you want for each story."