Bell died around 10 a.m. of kidney failure, said Diana Lewis, a spokeswoman for Piedmont Hospital. He was being treated at the Atlanta hospital for complications due to pancreatic cancer and kidney disease, which he had fought for years, she said.
Carter said he was "deeply saddened" by Bell's death and called him a "trusted and enduring public figure."
"As a World War II veteran, federal appeals court judge, civil rights advocate, and U.S. attorney general in my administration, Griffin made many lasting contributions to his native Georgia and country," he said in a statement. "Our thoughts and prayers are with his family."
Carter's choice of his longtime friend as attorney general was considered the most controversial of his Cabinet appointments after the 1976 election.
The NAACP and other civil rights groups complained that Bell, as a federal judge, didn't force Southern schools to integrate quickly enough. And they cited Bell's tenure as chief of staff for Georgia Gov. Ernest Vandiver, who campaigned in 1958 on a segregation platform.
But Carter called Bell's civil rights record superb, and many black Georgians - including U.N. ambassador designate Andrew Young - came forward to support him.
"Frankly, I prefer a Southerner who has been struggling with the problem of civil rights actively for several years over a Northern intellectual liberal," Young said at the time.
Bell served just 2½ years at the Justice Department, leaving in mid-1979 - at his own request - to return to his Atlanta law firm, King & Spalding. But he called his tenure as attorney general "the best job I ever had," and he remained close to the action in government by maintaining a law office in Washington. He also remained a key adviser to Carter.
As attorney general, Bell promoted judicial reform and supported the Foreign Intelligence Surveillance Act, which limits government spying on U.S. citizens. He also investigated Koreagate, the alleged buying of congressional influence by Korean agents, and set in motion the investigation that led to a bank fraud indictment against fellow Georgian Bert Lance, Carter's budget chief. Lance was later acquitted.
Bell was born Oct. 31, 1918, in the south Georgia town of Americus, 10 miles from Carter's hometown of Plains. Their families were well acquainted even though he was six years older than Carter.
While attending public schools and Georgia Southwestern College in Americus, Bell worked part-time in his father's service station and appliance store.
He joined the Army in 1941, before the United States entered World War II, and served five years in the transportation corps, rising from private to major. After the war, he attended law school at Mercer University in Macon, graduating with honors in 1948. He practiced law in Savannah and Rome before joining King & Spalding, an Atlanta law firm known for its corporate clients and political connections. He worked there for more than 40 years.
A sharp dresser with a Southern drawl, Bell was more sought-after than many Wall Street lawyers. His reputation for integrity and his status as a former attorney general brought him many high-profile cases.
He was hired by E.F. Hutton to investigate charges that some members of the brokerage firm had engaged in complex fraud schemes. He also headed investigations into the Exxon Valdez oil spill in Alaska, and Procter & Gamble Co. hired him to sue people who circulated false rumors that the company's moon-and-stars logo was a satanic symbol.
In 1986, he went to Nicaragua to help represent captured American mercenary Eugene Hasenfus. And in 1992, President George H. W. Bush hired Bell to be his private lawyer in the Iran-Contra scandal.
His support of Vandiver in Georgia's 1958 governor's race won him the appointment as chief of staff and placed him in the middle of the school desegregation fight. Bell negotiated with black leaders to avoid violence and initiated the Sibley Commission, which held statewide public hearings on integration.
Vandiver, whose campaign slogan of "No, Not One" signified his intent to keep Georgia's schools from integrating, eventually backed off and pushed the Legislature to repeal state segregation laws.
"I think maybe the reason he put me in there was because I had told him privately I thought he was making a grave mistake taking such a strong position," Bell recalled during an interview in the New York Times Magazine in 1977.
In 1961, President Kennedy appointed Bell to the 5th U.S. Circuit Court of Appeals in New Orleans. He served there for 15 years, building a record as a moderate who shied away from busing as a means of school desegregation.
His rulings generally supported civil rights in employment and voting cases, and he wrote opinions in defense of civil rights demonstrations.
"I've always believed I should be moderate on the bench," he told the Senate Judiciary Committee during hearings on his confirmation as attorney general.
Bell's latest book "Footnotes to History: A Primer on the American Political Character," recently was published by Mercer University Press. It is a collection of speeches he gave during his long career. Originally scheduled for release this spring, the publisher pushed up the release date after Bell's health declined.
Bell continued to practice law well after his 80th birthday, despite battling kidney disease and pancreatic cancer in recent years. A steady stream of family and friends had trekked down to his Americus home over the last few months to pay their respects.
"He was the very same man I met here in 1983," said Robert Hays, chairman of King & Spalding, who visited Bell in November. "To a person, everyone remarked that he had not missed one step during any of his time. He ended his life with as much clarity and insight as he ever had."