He was hospitalized at Vanderbilt University Medical Center April 18 for fever and irregular blood pressure, publicist Kirt Webster of Webster & Associates said in a statement.
Jones was in the middle of a tour that he said would be his last when he fell ill. Several dates had already been canceled.
"My heart is absolutely broken. George Jones was my all time favorite singer," country music singer Dolly Parton said in a Twitter message.
Jones -- a Texas native, born Sept. 12, 1931, with a broken arm in an oil town near Beaumont -- had No. 1 songs in five separate decades, 1950s to 1990s. Only "Nashville sound" singer Eddy Arnold had more Top Ten hits, and Jones always stayed closer to the roots of hardcore country.
His heartbreaking 1980 classic "He Stopped Loving Her Today" often tops industry lists of the greatest country music singles of all time.
Jones' other hits included "White Lightning," "The Grand Tour," "Golden Ring" and "Why Baby Why."
Overall, he charted 160 songs.
Late country singer Waylon Jennings expressed a common jealousy in his song "It's Alright."
"From the Beatles and me in Nashville, to the billies and the Rolling Stones / If we all sounded like we wanted to, we'd all sound like George Jones."
Country music historian Bill C. Malone wrote, "For the two or three minutes consumed by a song, Jones immerses himself so completely in its lyrics, and in the mood it conveys, that the listener can scarcely avoid becoming similarly involved."
Jones often made headlines as much for tales of his drinking, stormy relationships with women and violent rages as for his prolific recording and touring.
He was married four times, including to fellow country singer Tammy Wynette.
His wild lifestyle led to his missing many performances, earning him the nickname "No Show Jones." The license plates on his cars eventually read "NOSHOW1" to "NOSHOW7," The New York Times said.
Jones' pointed nose and close-set eyes originally gave him the nickname "The Possum."
In the last 10 years, he recorded with Shooter Jennings and Staind frontman Aaron Lewis, as well as with Parton and Merle Haggard, who said Friday: "The world has lost the greatest country singer of all time. Amen."
Ray Price, a contemporary of Jones said "the door to an era in time is slowly closing. With only a handful of us left standing, the country music I knew and loved gas also passed away. It is my great hope that the younger generation of singers will remember all of us from that and carry on."
Alan Jackson said Jones was "the greatest singer of real country music -- there'll never be another."
"Heaven better get ready for George Jones," Jackson said.
"If I'm blessed enough to make it there, I look forward to you giving me the grand tour," Keith Urban said.
"I believe if you ask any singer who was the greatest country music singer of all time, they would say 'George Jones,'" said Barbara Mandrell. "He was without question and by far the Best!"
Inducted into the Country Music Hall of Fame in 1992 and named a Kennedy Center Honoree in 2008, Jones was presented with a Grammy Lifetime Achievement award last year.
He is survived by his wife of 30 years Nancy; his sister Helen Scroggins and his children and grandchildren, the Webster & Associates website says.