Evora, known as the "Barefoot Diva" because she always performed without shoes, died at a hospital in Mindelo, on her native island of Sao Vicente in Cape Verde, her label Lusafrica announced on its website. It gave no further details.
Evora retired after having a stroke in September. A heavy smoker, she was diagnosed with heart problems in 2005 and had open-heart surgery last year.
She sang traditional music of the Cape Verde archipelago, a former Portuguese colony. She mainly sang in a language known as Crioulo, a Portuguese Creole sprinkled with West African words. Even audiences who couldn't understand the lyrics were moved by her stirring renditions, her unpretentious manner and the music's infectious beat.
Her singing style brought comparisons to American jazz singer Billie Holiday and the great French singer Edith Piaf.
"She belongs to the aristocracy of bar singers," French newspaper Le Monde said in 1991, adding that Evora had "a voice to melt the soul."
Evora's international fame came late in life. Her 1988 album "La Diva Aux Pieds Nus" ("Barefoot Diva"), recorded in France where she first found popularity, launched her international career.
Her 1995 album "Cesaria" was released in more than a dozen countries and brought her first Grammy nomination, leading to a major concert tour and album sales in the millions.
She received a Grammy in the World Music category in 2004 for her album "Voz D'Amor."
Evora was the best-known performer of the bittersweet "morna," the national music of Cape Verde. It is a complex, soulful sound, mixing an array of influences arising from the African and seafaring traditions of the 10 volcanic islands.
Evora was born Aug. 27, 1941, on the island of Sao Vicente. Her mother was a cook and her father was a musician who played guitar and violin.
She grew up in Mindelo, a port city on the island where sailors from Africa, America, Asia and Europe mingled in what was a lively cosmopolitan town with a fabled night life. The local musical style borrowed from those cultures, defying attempts to classify it.
"Our music is a lot of things," Evora told the Associated Press in 2000. "Some say it's like the blues, or jazz. Others says it's like Brazilian or African music, but no one really knows."
Evora was 7 years old when her father died, leaving behind seven children. When her mother was unable to make ends meet, Evora was placed in an orphanage at age 10.
At 16, when Evora was doing piecework as a seamstress, a friend persuaded her to sing in one of the many sailors' taverns in her town. She soon was performing all over the islands and became a local star.
After Cape Verde gained independence from Portugal in 1975, the nightclub scene waned. Evora "had three children from three different fathers," she later said, and was struggling to raise a family. One of her children died of a fever.
At 34, Evora quit performing and moved in with her mother.
A decade later, she came out of retirement when a group of Cape Verdean women in Portugal offered to bring her to Lisbon. By the 1990s, Evora was an international star known for never wearing shoes onstage. There was no higher calling to her shoelessness, no showing of solidarity with the hungry and the poor, she had said.
"In Cape Verde, lots of people are like me," she told the Washington Post in 2001. "They just don't like to wear shoes."
Information on survivors was not immediately available.