Literary agency Curtis Brown said the author, real name David John Moore Cornwell, died on Saturday evening after a short illness which was not related to Covid-19.
A statement shared on behalf of his family said: “It is with great sadness that we must confirm that David Cornwell – John le Carre – passed away from pneumonia last Saturday night after a short battle with the illness.
“David is survived by his beloved wife of almost 50 years, Jane, and his sons Nicholas, Timothy, Stephen and Simon.
“We all grieve deeply his passing. Our thanks go to the wonderful NHS team at the Royal Cornwall Hospital in Truro for the care and compassion that he was shown throughout his stay. We know they share our sadness.”
Cornwell, who worked for both the Security Service (MI5) and the Secret Intelligence Service (MI6), wrote a number of international best-selling espionage novels which were later adapted for film or television.
His best-known works included The Spy Who Came in from the Cold, The Night Manager and The Constant Gardener.
“John le Carre was an undisputed giant of English literature,” Jonny Geller, CEO of the Curtis Brown Group, said in a statement.
“He defined the Cold War era and fearlessly spoke truth to power in the decades that followed.”
Mr Geller added: “I represented David for almost 15 years. I have lost a mentor, an inspiration and most importantly, a friend. We will not see his like again.”
In a tribute on Twitter, author Stephen King described him as “a literary giant and a humanitarian spirit”.
Cornwell, who was born in Poole, Dorset in 1931, was understood to have had a difficult relationship with his father, a con man who spent time in jail for insurance fraud, and his mother, who left the family when he was five years old.
He studied in Switzerland as a young man and completed compulsory military service in Austria before taking a degree in modern languages at the University of Oxford in the early 1950s.
From there, he went on to teach French and German at Eton College and worked in the British intelligence service until his career in espionage was ended when his name was revealed to the KGB by British double agent Kim Philby.
Although Cornwell drew on his experience working for the British intelligence services in his writing, he later became frustrated at the extent to which his novels were portrayed as representing real-world spying.
He said his manuscript for The Spy Who Came In From The Cold was approved by the secret service in 1963 because they “rightly if reluctantly” concluded it was “sheer fiction from start to finish” and therefore posed no security risk.
However, he said the world’s press took a different view and decided the book represented “some kind of revelatory Message From The Other Side”.
“From the day my novel was published, I realised that now and forever more I was to be branded as the spy turned writer, rather than as a writer who, like scores of his kind, had done a stint in the secret world, and written about it,” he wrote in The Guardian in 2013.
Additional reporting by PA