The leather-clad would-be Elvis, known simply as Johnny, announced in March he had been diagnosed with the disease and would undergo treatment.
“Johnny Hallyday has left us. I write these words without believing them. But yet, it's true. My man is no longer with us,” said Laeticia Hallyday, 42, in a statement made in the early hours.
“He left us tonight as he lived his whole life, with courage and dignity.”
While he was never taken seriously abroad, Hallyday broke from France's classic “chanson” tradition in the late 1950s, selling more than 100 million albums and headlining 50 major tours.
Born on June 15 1943, he attempted suicide in 1966, collapsed on stage in 1986 and married five times, twice to the same woman, the daughter of one of his oldest friends and songwriters.
President Emmanuel Macron was among the first to react to Hallyday's death, saying: “There is something of Johnny in all of us.”
On a tous en nous quelque chose de Johnny. https://t.co/1z35AuH4bJ
— Emmanuel Macron (@EmmanuelMacron) December 6, 2017
The world of French music and culture lined up to pay tribute to Hallyday.
“I have lost more than a friend. I have lost a brother,” French singer Eddy Mitchell told AFP. “
Former culture minister Jack Lang said: “He was a part of all of us. It's difficult to imagine that we won't ear his voice again.”
I'm very sad to hear the news that Johnny Hallyday passed away. He was a giant in show business…a true icon! My thoughts go out to his family, his loved ones, and to the millions of fans who adored him for many decades.He will be sadly missed, but never forgotten.- Céline xx…
— Celine Dion (@celinedion) December 6, 2017
Farewell Dear @JohnnySjh. Your friendship, sweetness and support are imprinted in my heart. It is an honor to have known you and to have spent time with you and your beautiful family. Your soul is pure Rock and Roll. Repose en paix. ?: @candyTman pic.twitter.com/1ZAFUewHlo
— Lenny Kravitz (@LennyKravitz) December 6, 2017
Politicians also paid tribute to the French singing legend.
«Que je t’aime! Que je t’aime! » C’est ce que chaque Français a envie de déclarer à Johnny ce matin. Comme il le disait lui-même, il faisait partie de notre vie.
— Alain Juppé (@alainjuppe) December 6, 2017
Rumours of Hallyday's passing had flown online in recent weeks after he was admitted to hospital in Paris with breathing problems.
Hallyday, whose real name was Jean-Philippe Smet, spent six days under medical care before returning to rest at his home in Marnes-la-Coquette, west of the capital.
“Until the very last moment, he held firm against this illness that had afflicted him for months, teaching us all extraordinary life lessons,” said Laeticia Hallyday.
The rocker “lived his entire life wholly for his fans, who loved him and idolised him”, she added.