Lieberman was the Democratic Party's vice presidential nominee under Al Gore in the 2000 election, becoming the first Jewish candidate on a major party presidential ticket in the U.S.
His family said that he had been suffering complications from a fall, and was with loved ones when he passed away.
Lieberman and Gore ultimately lost to Republican George W. Bush.
Four years later, Lieberman failed in a bid for the 2004 Democratic presidential nomination, hurt by his support for the Iraq War.
Lieberman was a centrist from Connecticut, and first elected to the U.S. Senate in 1988.
He lost that seat in the 2006 Democratic primary, but retained the seat by winning the general election as an independent candidate.
He broke further from the Democratic Party in 2008 when he endorsed Republican John McCain for president.
However, he went on to back the presidential bids of Democrats Hillary Clinton in 2016 and Joe Biden in 2020.
Lieberman retired from the Senate in 2013 after four six-year terms.
Most recently, Lieberman was leading "No Labels", a centrist group that hopes to launch an outsider bid for the White House.
Lieberman's funeral is set for Friday in his hometown of Stamford.
