"We are absolutely heartbroken," his wife Patti told the Los Angeles Times, blaming his chronic obstructive pulmonary disease on a lifetime of cigarette smoking. "He fought long and hard."
Phil Everly last performed in public in 2011, but his son Jason said he had been actively writing songs. He said his father had been in the hospital in Burbank for about two weeks when he died.
The music of Everly, 74, who took the high notes, and his brother Don influenced the Beatles, the Beach Boys, the Byrds and many other rock, country and folk singers. Their hits included Cathy's Clown, Wake Up Little Susie, Bye Bye Love, When Will I Be Loved and All I Have To Do Is Dream.
In the late 1950s and 1960s, the Everly Brothers fused rock 'n' roll with their high harmony, while their poignant lyrics captured the restlessness and energy of a generation.
Their career spanned five decades, although they performed separately from 1973 to 1983. In their heyday between 1957 and 1962, they had 19 top 40 hits.
The Everlys dealt in the entire emotional spectrum with an authenticity that appealed to proto rockers like the Beatles and Bob Dylan, who gladly pass the credit for the sea changes they made in rock to the ruggedly handsome brothers.
The Beatles once referred to themselves as "the English Everly Brothers" and Dylan, pop culture's poet laureate, once said: "We owe these guys everything. They started it all."
Two generations later, artists are still finding inspiration in the music. Most recently, Green Day's Billie Joe Armstrong and Norah Jones lovingly recorded a tribute to the Everlys and their unique album Songs Our Daddy Taught Us.
"There's so much darkness in those old songs," Armstrong said recently. "I think mainly that's just how people communicated when it came to mourning and loss. Then with the Everly Brothers it sounds like these two little angels that sing."
But the two broke up amid quarrelling in 1973 after 16 years of hits, then reunited in 1983, "sealing it with a hug", Phil said.
Although their number of hit records declined in the late 1980s, they made successful concert tours in the US and Europe.
They were inducted into the Rock 'n' Roll Hall of Fame in 1986, the same year they had a hit pop-country record, Born Yesterday.
Don Everly was born in 1937 in Brownie, Kentucky, to Ike and Margaret Everly, who were folk and country music singers. Phil was born in 1939 in Chicago, where the Everlys moved to when their father grew tired of working in the coal mines.
The brothers began singing country music in 1945 on their family's radio show in Shenandoah, Iowa. Their career breakthrough came when they moved to Nashville in the mid-1950s and signed a recording contract with New York-based Cadence Records.
Their break-up came dramatically during a concert at Knott's Berry Farm in California. Phil Everly threw his guitar down and walked off, prompting Don Everly to tell the crowd: "The Everly Brothers died 10 years ago."
During their break-up they pursued solo singing careers with little fanfare. Phil also appeared in the Clint Eastwood movie Every Which Way But Loose. Don made a couple of records with friends in Nashville, performed in local nightclubs and played guitar and sang background vocals on recording sessions.
In 1986 Don Everly said the two were successful because "we never followed trends. We did what we liked and followed our instincts. Rock 'n' roll did survive, and we were right about that. Country did survive, and we were right about that. You can mix the two but people said we couldn't".
In 1988, the brothers began hosting an annual homecoming benefit concert in Central City, Kentucky, to raise money for the area.