Frey died in New York City of complications from rheumatoid arthritis, acute ulcerative colitis and pneumonia, the band said.
The Eagles, whose album, “Their Greatest Hits 1971-1975,” is the second-best-selling record of all time in the United States, helped create the freewheeling soundtrack of 1970s America and remain ubiquitous on rock radio nearly half a century later.
Their blend of rock with country music influences fueled their success with hit songs such as “Desperado,” “Already Gone” and “Take It to the Limit.”
Frey collaborated with drummer Don Henley to co-write many of the band’s biggest hits. While Henley most often sang lead vocals for the band, Frey played guitar and piano, was key to the band’s harmony as a back-up vocalist, and at times sang lead.
His performances on “Take It Easy” and “Peaceful Easy Feeling” on the band’s debut album in 1972 helped rocket the Eagles to fame, and he later sang lead on hits “Lyin’ Eyes” and “Already Gone.”
Frey died a little more than a week after another rock great, David Bowie, died at age 69 in New York, apparently of liver cancer.
Detroit-born Frey and Henley co-founded the Eagles in 1971 in Los Angeles after playing backup for rock singer Linda Ronstadt.
Henley in a statement praised Frey as the “one who started it all” for the Eagles.
“He was the spark plug, the man with the plan,” Henley said. “He had an encyclopedic knowledge of popular music and a work ethic that wouldn’t quit. He was funny, bullheaded, mercurial, generous, deeply talented and driven.”
The band’s original members also included Bernie Leadon and Randy Meisner. Several other musicians, including Joe Walsh, joined in the 1970s.
After the Eagles disbanded in 1980, Frey had a successful solo career, recording the songs “The One You Love” and “The Heat Is On.” Several of his compositions were for films or TV shows, and Frey took on a side career as an actor, including a small part in 1996 film “Jerry Maguire.”
In 1994, the Eagles reunited and released an album titled “Hell Freezes Over.” The name jokingly referred to Henley’s previous statement that the band would only get back together when “hell freezes over.”
Henley said he viewed Frey as a kind of brother, but acknowledged that, like in many families, “there was some dysfunction” in the relationship.
The Eagles, who were inducted into the Rock and Roll Hall of Fame in 1998 and have played many sold-out shows since their reunion, most recently completed a two-year tour last July.
Frey, in an interview with the Tampa Bay Times in 2012, credited his band members’ physical health as one reason for their success. “We managed to get off the party train pretty early,” he told the paper.
But last year, Frey’s health took a bad turn, as he suffered from intestinal problems.
The Eagles had been slated to join songwriter Carole King, “Star Wars” director George Lucas and others in receiving the prestigious Kennedy Center Honors in Washington last month. But in November, the center announced the Eagles could not participate because of Frey’s health, and said the award would be presented in 2016.
“Thank you for the music that paved the way for so many others,” country star Brad Paisley said in praising Frey on Twitter.
Frey is survived by his wife, Cindy, and their three children.