Mondale, an entertainment reporter and radio show host, died in her sleep with her husband and dogs at her side, according to a statement posted on her journal page at the website CaringBridge.org.
"Early Saturday morning . . . our dearest sweet Eleanor passed away from this world," the journal entry said. "Eleanor Mondale Poling lived bravely, without regret or fear, with such amazing strength and grace, for 6 years after being diagnosed with brain cancer in 2005."
Mondale was the daughter of Joan and Walter Mondale; her father was vice president under president Jimmy Carter. She also was the ex-wife of former pro football player Keith Van Horne.
Married two more times, Mondale in 2005 wed Minneapolis musician Chan Poling.
She was a graduate of St. Lawrence University in Canton, N.Y. Her career included minor acting roles on television shows and stints as a TV news reporter. She had bit parts in TV's "Three's Company" and "Dynasty."
A striking blonde known on the party circuit when she was younger, Mondale's dalliance with musician Warren Zevon was detailed in "I'll Sleep When I'm Dead: The Dirty Life and Times of Warren Zevon," a posthumous biography published by Zevon's ex-wife in 2007.
She got her start in broadcasting at WCCO-TV in Minneapolis in 1989 but left after eight months when a magazine was about to publish an article called "Walter and Joan's Wild Child."
Minnesota Gov. Mark Dayton released a statement mourning Mondale's death. "Eleanor transformed -- and transcended! -- into a very beautiful, poised, multi-talented, and accomplished woman," he said. "She loved her family, friends, and animals, as she loved life."