On Friday the hospital released a statement confirming her death but declined to provide further details.
Known for her stylishness and her exciting way of playing, she was the first South American woman to win the Wimbledon singles title.
The Brazilian tennis legend was nicknamed the "Tennis Ballerina" for the effortless grace she exhibited on court.
Bueno was also a prolific doubles player, claiming women's titles at all four of the grand slams from 1958-68 and a mixed doubles championship at Roland Garros in 1960.
Maria Bueno was a Brazilian tennis star who was one of top players of the 1950s and 1960s.
"She was very courageous", her nephew Pedro Bueno said.
One tennis writer, John Barrett, called her "the elegant queen of Brazilian tennis". In his authoritative Tennis Encyclopedia, Bud Collins called Ms. Bueno "incomparably balletic and flamboyant" and said she played "with breathtaking boldness and panache".
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A tweet posted on the official Tennis Hall of Fame account referred to Bueno as an "accomplished champion who leaves a lasting legacy of inspiration to generations". She attributed her speed on the court to having trained with men.
Her last major title came in 1968 when she won the doubles title at the U.S. Open alongside Margaret Court - one of her biggest rivals in singles.
She was labelled the "Sao Paulo Swallow" for her ability to dominate the net by former BBC Sport commentator John Barrett.
However, her career was hampered right at the start of the Open Era, when she suffered arm and leg injuries.
In 1962, designer Ted Tinling created several outfits for Ms. Bueno with colored skirt linings and underpants, in violation of a Wimbledon rule that players dress entirely in white.
"Later I wore panties that resembled the club colors, which outraged the club committee and they brought in the all-white clothing rule".
"She had this fantastic brooding character, the impression of an imminent storm", Tinling told Sports Illustrated in 1969, "and I had to illustrate that in some way".