Carson's death came three weeks after she announced she had been diagnosed with terminal lung cancer and followed years of health troubles. She said days later that she would not run next year for a seventh term representing the district that covers most of Indianapolis.
She had not been in Washington since September, when she was hospitalized with a leg infection.
Carson was first elected to Congress in 1996. She championed children's issues, women's rights and efforts to reduce homelessness and was a staunch opponent of the war in Iraq.
"Julia Carson overcame much and accomplished much, and devoted her life to helping other people do the same," Sen. Evan Bayh, an Indiana Democrat, said in a statement. "She was elected to important public offices, but never forgot who she was, where she came from or who she was there to serve."
Carson was a staunch opponent of the war in Iraq and told hundreds of people at a rally in downtown Indianapolis just weeks before the 2003 invasion that it was an act of aggression only to protect U.S. oil interests.
"Truly, it is all in the name of greed and truly in the name of war," she said. "We should have learned by the Vietnam War, but we did not."
Carson was born to a single mother who worked as a housekeeper. She graduated in 1955 from the same segregated high school as basketball star Oscar Robertson.
She began her political career in the 1960s when then-Rep. Andy Jacobs Jr. hired her to work in his office. Jacobs encouraged Carson to run for the Indiana Legislature in 1972 – the first of more than two dozen victories in local, legislative and congressional elections. She ran for Congress in 1996 after Jacobs retired.
She also had suffered in recent years from high blood pressure, asthma and diabetes. She missed dozens of House votes in 2004 because of illness and spent the weekend before the 2004 election in the hospital for what she said was a flu shot reaction – but still won re-election by 10 percentage points.
Gov. Mitch Daniels will have to call a special election to choose a replacement for the last year of Carson's term.
Funeral arrangements were pending.