"Joni was found unconscious in her home this afternoon," said a statement on the Mitchell website. "She is currently in intensive care undergoing tests and is awake and in good spirits."
It wasn't immediately clear what illness she had.
Los Angeles fire officials said paramedics answered an afternoon 911 call in Bel Air, where Mitchell lives, and took a patient to the hospital. But they could not verify her identity or give details on her condition.
The 71-year-old singer-songwriter told Billboard magazine in December that she has a rare skin condition, Morgellons disease, which prevents her from performing. Still, she released a career-spanning four-disc box set last year and appeared at Clive Davis' annual pre-Grammy party in February.
Mitchell has received eight Grammy Awards, including a lifetime achievement award in 2002. She was inducted into the Rock and Roll Hall of Fame in 1997.
Joni has been hospitalized. We are awaiting official word on her condition and will post it here as soon as we know.— JoniMitchell.com (@JoniMitchellcom) April 1, 2015
She started her career as a street musician in her native Canada before moving to Southern California, where she became part of the flourishing folk scene in the late 1960s. Her second album, "Clouds," was a breakthrough with such songs as "Both Sides Now" and "Chelsea Morning," winning Mitchell the Grammy for best folk performance. Her 1970 album, "Ladies of the Canyon," featured the hit single "Big Yellow Taxi" and the era-defining "Woodstock." The following year, she released "Blue," which ranks 30th on Rolling Stone magazine's list of the "500 Greatest Albums of All Time."
Mitchell has released 19 original albums, the most recent in 2007. The anthology released last year, "Love Has Many Faces: A Quartet, A Ballet, Waiting to Be Danced," features remastered versions of 53 of her songs.
Her musical style integrates folk and jazz elements, and she counts jazz giants Charles Mingus and Pat Metheny among her past collaborators.
As with music, Mitchell taught herself painting as a child and has produced hundreds of works in ink, watercolor and acrylic.