Osborne became a beloved icon to a legion of groupies with gray hair as host of the Turner Classic Movies.
"Robert was embraced by devoted fans who saw him as a trusted expert and friend," TCM general manager Jennifer Dorian said in a statement, adding that Osborne's contributions were fundamental in shaping TCM into what it is today.
Osborne began his career as an actor. He was mentored by the legendary comedienne Lucille Ball.
He would, later on, become the official biographer of the Oscars thanks to a series of books he wrote about the Academy Awards.
In 1977, Osborne joined The Hollywood Reporter to write reviews. He wrote the paper's Rambling Reporter column from April 1983 until he left the publication in June 2009.
When Ted Turner's TCM debuted on April 14, 1994, Osborne was on air to introduce the station's first film, Gone With the Wind.
He stayed with TCM as primetime host from there on, introducing and providing insightful nuggets of information for many of the 400 or so movies that TCM shows every year.
He missed the 2015 TCM Classic Film Festival after announcing at the last minute that doctors had advised him to have an undisclosed medical procedure that he had postponed.
Less than three weeks into the 2016 event, he pulled out again, saying that a health issue which required urgent attention had come up.
The Journalist was 84.