Caballe's family has reportedly requested the cause of death not be released, though revealed she had been in hospital since last month.
A service for the singer, who has long suffered from health problems, will be held tomorrow with a funeral on Monday, according to Barcelona authorities.
Madrid's Teatro Real said it would dedicate Saturday's performance of "Faust" to the memory of Caballe, lauding the "singular beauty of her voice" and her prodigious technique.
Spanish President Pedro Sanchez paid tribute to Caballe on Saturday, saying on Twitter that Spain had lost "a great ambassador of our country, a soprano recognised internationally".
"Her loss leaves a huge void", he said.
She began in the Swiss city in 1956, as Mimi in La Bohème, then joined the Bremen Opera, where she sang from 1959 to 1962, in a wide variety of roles.
She had stints with the Basel Opera and Bremen Opera before her global breakthrough in 1965 in Lucrezia Borgia at Carnegie Hall in NY.
She went on to tour the world in a career spanning 50 years, garnering worldwide acclaim for her creamy voice and dramatic power.
Her voice was described by her fans as inspirational, legendary and not of this world.
The performance won her great acclaim from the public and made her an overnight sensation.
In a brief excursion into pop music, Caballe's duet "Barcelona" with Freddie Mercury, of the rock group Queen, was a hit single in 1987, accompanied by an album of the same name.
The duo played a leading role in what was the official anthem of the Olympics in Barcelona in 1992.
In 2015, she was convicted of tax fraud and given a suspended sentence of six months in prison.
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