His wife Hadassah and members of his family were with him when he died in New York City, a family statement said on Wednesday.
Lieberman was the Democratic Party's vice-presidential nominee in the 2000 election, which was won by Republican George W Bush by a narrow margin over Democrat Al Gore after a drawn-out recount, legal challenges and a Supreme Court decision.
Lieberman was the first Jewish candidate on a major party presidential ticket in the US.
He failed in a bid for the 2004 Democratic presidential nomination, hurt by his support for the Iraq War.
Lieberman's "strong will made him a force to be reckoned with", Al Gore said. (AP PHOTO)
"Joe was a man of deep integrity who dedicated his life to serving his country," Gore said in a statement.
"He was a truly gifted leader, whose affable personality and strong will made him a force to be reckoned with.
"That's why it came as no surprise to any of us who knew him when he'd start singing his favourite song: Frank Sinatra's My Way.
"And doing things Joe's way meant always putting his country and the values of equality and fairness first."
A centrist, Lieberman was first elected to the US Senate in 1988.
He lost the state's Democratic primary in 2006, but retained his seat by winning the general election as an independent candidate.
In a further break from the Democratic Party, Lieberman endorsed Republican senator John McCain for president in a speech at the Republican National Convention in 2008.
But Lieberman would later back Democrats Hillary Clinton in 2016 and Joe Biden in 2020 in their bids for the presidency.
Lieberman retired from the Senate in 2013 after four six-year terms.
"Joe was as fine an American as they come and one of the most decent people I met during my time in Washington," Republican former president George W Bush said in a statement.
Most recently, Lieberman was leading No Labels, a centrist group that hopes to launch an outsider bid for the White House.
Lieberman, who held a law degree from Yale Law School, was a member of the Connecticut State Senate and then attorney-general of Connecticut before becoming a US senator.
Lieberman had three children from two marriages; his first marriage ended in divorce.
Lieberman's funeral is set for Friday in his hometown of Stamford, Connecticut.
Reuters and AP
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